Ethane, hexachloro-

Data at NIST subscription sites:

NIST subscription sites provide data under the NIST Standard Reference Data Program, but require an annual fee to access. The purpose of the fee is to recover costs associated with the development of data collections included in such sites. Your institution may already be a subscriber. Follow the links above to find out more about the data in these sites and their terms of usage.


Gas phase thermochemistry data

Go To: Top, Phase change data, Gas phase ion energetics data, IR Spectrum, Vibrational and/or electronic energy levels, Gas Chromatography, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
DRB - Donald R. Burgess, Jr.
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein

Quantity Value Units Method Reference Comment
Δfgas-32.079kcal/molReviewChase, 1998Data last reviewed in September, 1967
Δfgas-35.4 ± 1.4kcal/molReviewManion, 2002weighted average of several measurements of equilibria involving C2Cl6, CCl4, and C2Cl4; DRB
Δfgas-34.3 ± 2.3kcal/molEqkPuyo, Balesdent, et al., 1963Reanalyzed by Cox and Pilcher, 1970, Original value = -34.7 ± 1.0 kcal/mol; ALS
Quantity Value Units Method Reference Comment
gas,1 bar95.086cal/mol*KReviewChase, 1998Data last reviewed in September, 1967

Gas Phase Heat Capacity (Shomate Equation)

Cp° = A + B*t + C*t2 + D*t3 + E/t2
H° − H°298.15= A*t + B*t2/2 + C*t3/3 + D*t4/4 − E/t + F − H
S° = A*ln(t) + B*t + C*t2/2 + D*t3/3 − E/(2*t2) + G
    Cp = heat capacity (cal/mol*K)
    H° = standard enthalpy (kcal/mol)
    S° = standard entropy (cal/mol*K)
    t = temperature (K) / 1000.

View plot Requires a JavaScript / HTML 5 canvas capable browser.

View table.

Temperature (K) 298. to 1200.1200. to 6000.
A 31.1684046.13241
B 28.67139-1.441850
C -24.101410.241066
D 7.204281-0.014623
E -0.405846-2.449080
F -43.81341-52.07151
G 122.9810142.3080
H -32.08009-32.08009
ReferenceChase, 1998Chase, 1998
Comment Data last reviewed in September, 1967 Data last reviewed in September, 1967

Phase change data

Go To: Top, Gas phase thermochemistry data, Gas phase ion energetics data, IR Spectrum, Vibrational and/or electronic energy levels, Gas Chromatography, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
TRC - Thermodynamics Research Center, NIST Boulder Laboratories, Chris Muzny director
DRB - Donald R. Burgess, Jr.
AC - William E. Acree, Jr., James S. Chickos
ALS - Hussein Y. Afeefy, Joel F. Liebman, and Stephen E. Stein
CAL - James S. Chickos, William E. Acree, Jr., Joel F. Liebman, Students of Chem 202 (Introduction to the Literature of Chemistry), University of Missouri -- St. Louis
DH - Eugene S. Domalski and Elizabeth D. Hearing

Quantity Value Units Method Reference Comment
Tboil458.KN/ALecat, 1927Uncertainty assigned by TRC = 1. K; TRC
Tboil458.KN/ALecat, 1926Uncertainty assigned by TRC = 1. K; TRC
Quantity Value Units Method Reference Comment
Tfus458. ± 4.KAVGN/AAverage of 7 values; Individual data points
Quantity Value Units Method Reference Comment
Δvap12. ± 0.55kcal/molReviewManion, 2002estimated from Tb using DvH/Tb correlation for other chloroethanes; DRB
Quantity Value Units Method Reference Comment
Δsub14.1 ± 0.2kcal/molVIvin and Dainton, 1947ALS

Enthalpy of vaporization

ΔvapH (kcal/mol) Temperature (K) Method Reference Comment
9.63475.AStephenson and Malanowski, 1987Based on data from 460. to 513. K.; AC
12.2360.AStephenson and Malanowski, 1987Based on data from 345. to 460. K. See also Dykyj, 1970.; AC
12.8320.N/AStull, 1947Based on data from 305. to 458. K.; AC

Antoine Equation Parameters

log10(P) = A − (B / (T + C))
    P = vapor pressure (atm)
    T = temperature (K)

View plot Requires a JavaScript / HTML 5 canvas capable browser.

Temperature (K) A B C Reference Comment
305.9 to 458.84.205521626.945-76.102Stull, 1947Coefficents calculated by NIST from author's data.

Enthalpy of sublimation

ΔsubH (kcal/mol) Temperature (K) Method Reference Comment
14.1331.N/AStephenson and Malanowski, 1987Based on data from 317. to 345. K.; AC
12.1335. to 453.N/ALee, 1935AC
14.1310.GS,ANelson, 1930Based on data from 288. to 333. K.; AC

Enthalpy of fusion

ΔfusH (kcal/mol) Temperature (K) Reference Comment
2.33458.Domalski and Hearing, 1996AC

Entropy of fusion

ΔfusS (cal/mol*K) Temperature (K) Reference Comment
1.93318.Domalski and Hearing, 1996CAL
5.696345.
5.088458.

Temperature of phase transition

Ttrs (K) Initial Phase Final Phase Reference Comment
454.crystaline, IliquidMurrill and Breed, 1970DH

Enthalpy of phase transition

ΔHtrs (kcal/mol) Temperature (K) Initial Phase Final Phase Reference Comment
0.5019316.8crystaline, IIIcrystaline, IIPetropavlov, Tsygankova, et al., 1988DH
1.506345.0crystaline, IIcrystaline, IPetropavlov, Tsygankova, et al., 1988DH
0.6319317.4crystaline, IIIcrystaline, IIRakhmenkulov, Gutov, et al., 1975DH
1.653344.6crystaline, IIcrystaline, IRakhmenkulov, Gutov, et al., 1975DH
0.6226320.crystaline, IIIcrystaline, IIMurrill and Breed, 1970DH
1.508345.crystaline, IIcrystaline, IMurrill and Breed, 1970DH
0.6131318.crystaline, IIIcrystaline, IISeki and Momotani, 1950DH
1.965345.crystaline, IIcrystaline, ISeki and Momotani, 1950DH
2.330458.crystaline, IliquidSeki and Momotani, 1950DH

Entropy of phase transition

ΔStrs (cal/mol*K) Temperature (K) Initial Phase Final Phase Reference Comment
1.6316.8crystaline, IIIcrystaline, IIPetropavlov, Tsygankova, et al., 1988DH
4.37345.0crystaline, IIcrystaline, IPetropavlov, Tsygankova, et al., 1988DH
1.99317.4crystaline, IIIcrystaline, IIRakhmenkulov, Gutov, et al., 1975DH
4.80344.6crystaline, IIcrystaline, IRakhmenkulov, Gutov, et al., 1975DH
1.95320.crystaline, IIIcrystaline, IIMurrill and Breed, 1970DH
4.379345.crystaline, IIcrystaline, IMurrill and Breed, 1970DH
1.93318.crystaline, IIIcrystaline, IISeki and Momotani, 1950DH
5.69345.crystaline, IIcrystaline, ISeki and Momotani, 1950DH
5.50458.crystaline, IliquidSeki and Momotani, 1950DH

In addition to the Thermodynamics Research Center (TRC) data available from this site, much more physical and chemical property data is available from the following TRC products:


Gas phase ion energetics data

Go To: Top, Gas phase thermochemistry data, Phase change data, IR Spectrum, Vibrational and/or electronic energy levels, Gas Chromatography, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled as indicated in comments:
LLK - Sharon G. Lias, Rhoda D. Levin, and Sherif A. Kafafi
B - John E. Bartmess

Electron affinity determinations

EA (eV) Method Reference Comment
1.479 ± 0.095SIGaines, Kay, et al., 1966The Magnetron method, lacking mass analysis, is not considered reliable. G3MP2B3 calculations indicate an EA of ca. 1.1 eV.; B

Ionization energy determinations

IE (eV) Method Reference Comment
11.1PEKimura, Katsumata, et al., 1981LLK
11.22PEKimura, Katsumata, et al., 1981Vertical value; LLK
11.22PEKatsumata and Kimura, 1975Vertical value; LLK

IR Spectrum

Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, Vibrational and/or electronic energy levels, Gas Chromatography, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Gas Phase Spectrum

Notice: This spectrum may be better viewed with a Javascript and HTML 5 enabled browser.

IR spectrum
For Zoom
1.) Enter the desired X axis range (e.g., 100, 200)
2.) Check here for automatic Y scaling
3.) Press here to zoom

Notice: Concentration information is not available for this spectrum and, therefore, molar absorptivity values cannot be derived.

Additional Data

View image of digitized spectrum (can be printed in landscape orientation).

View spectrum image in SVG format.

Download spectrum in JCAMP-DX format.

Owner NIST Standard Reference Data Program
Collection (C) 2018 copyright by the U.S. Secretary of Commerce
on behalf of the United States of America. All rights reserved.
Origin NIST Mass Spectrometry Data Center
State gas
Instrument HP-GC/MS/IRD

This IR spectrum is from the NIST/EPA Gas-Phase Infrared Database .


Vibrational and/or electronic energy levels

Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, IR Spectrum, Gas Chromatography, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: Takehiko Shimanouchi

Symmetry:   D3d     Symmetry Number σ = 6


 Sym.   No   Approximate   Selected Freq.  Infrared   Raman   Comments 
 Species   type of mode   Value   Rating   Value  Phase  Value  Phase

a1g 1 CC str 975  C  ia 975 sln.
a1g 2 CCl3 str 431  C  ia 431 sln.
a1g 3 CCl3 s-deform 170  C  ia 170 sln.
a1u 4 Torsion 61  D  ia  ia
a2u 5 CCl3 s-str 675  C 675 S sln.  ia OC410411)
a2u 6 CCl3 s-deform 372  C 372 S sln.  ia
eg 7 CCl3 d-str 859  C  ia 859 sln.
eg 8 CCl3 d-str 340  C  ia 340 sln.
eg 9 CCl3 d-deform 223  C  ia 223 sln.
eu 10 CCl3 rock 778  C 778 VS sln.  ia
eu 11 CCl3 d-deform 271  C 271 S sln.  ia
eu 12 CCl3 rock 114  C 114 W sln.  ia

Source: Shimanouchi, 1972

Notes

VSVery strong
SStrong
WWeak
iaInactive
OCFrequency estimated from an overtone or a combination tone indicated in the parentheses.
C3~6 cm-1 uncertainty
D6~15 cm-1 uncertainty

Gas Chromatography

Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, IR Spectrum, Vibrational and/or electronic energy levels, References, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Data compiled by: NIST Mass Spectrometry Data Center, William E. Wallace, director

Kovats' RI, non-polar column, isothermal

View large format table.

Column type Active phase Temperature (C) I Reference Comment
PackedOV-1100.1068.Castello and Gerbino, 1988He, Chromosorb W DMCS; Column length: 3. m
PackedOV-1125.1081.Castello and Gerbino, 1988He, Chromosorb W DMCS; Column length: 3. m
PackedOV-175.1053.Castello and Gerbino, 1988He, Chromosorb W DMCS; Column length: 3. m

Kovats' RI, polar column, isothermal

View large format table.

Column type Active phase Temperature (C) I Reference Comment
PackedSP-1000100.1444.17Castello and Gerbino, 1988He, Chromosorb W DMCS; Column length: 3. m
PackedSP-1000125.1461.57Castello and Gerbino, 1988He, Chromosorb W DMCS; Column length: 3. m
PackedSP-100075.1426.53Castello and Gerbino, 1988He, Chromosorb W DMCS; Column length: 3. m

Van Den Dool and Kratz RI, non-polar column, temperature ramp

View large format table.

Column type Active phase I Reference Comment
CapillaryPetrocol DH1058.White, Hackett, et al., 1992100. m/0.25 mm/0.5 μm, He, 1. K/min; Tstart: 30. C; Tend: 220. C
PackedSE-301057.8Zilka and Matucha, 1978Ar, Chromaton N-AW-DMCS, 8. K/min; Column length: 2. m; Tstart: 40. C

Normal alkane RI, non-polar column, temperature ramp

View large format table.

Column type Active phase I Reference Comment
CapillaryOV-1011062.Zenkevich, Eliseenkov, et al., 201125. m/0.20 mm/0.25 μm, Nitrogen, 6. K/min; Tstart: 40. C; Tend: 220. C
CapillaryHP-11070.Boatright and Crum, 199730. m/0.25 mm/0.1 μm, He, 50. C @ 2. min, 5. K/min, 300. C @ 3. min
CapillaryHP-11070.Boatright and Crum, 199730. m/0.25 mm/0.1 μm, He, 50. C @ 2. min, 5. K/min, 300. C @ 3. min
CapillaryUltra-11056.Okumura, 199125. m/0.32 mm/0.25 μm, He, 3. K/min; Tstart: 80. C; Tend: 260. C
CapillarySE-541064.Harland, Cumming, et al., 1986He, 50. C @ 2. min, 8. K/min, 250. C @ 12. min; Column length: 25. m; Column diameter: 0.32 mm

Normal alkane RI, non-polar column, custom temperature program

View large format table.

Column type Active phase I Reference Comment
CapillaryMethyl Silicone1062.Zenkevich, 2001Program: not specified
CapillaryOV-11055.Waggott and Davies, 1984Hydrogen; Column length: 50. m; Column diameter: 0.32 mm; Program: not specified
CapillaryOV-1, SE-30, Methyl silicone, SP-2100, OV-101, DB-1, etc.1055.Waggott and Davies, 1984Hydrogen; Column length: 50. m; Column diameter: 0.32 mm; Program: not specified
CapillaryOV-1, SE-30, Methyl silicone, SP-2100, OV-101, DB-1, etc.1057.Waggott and Davies, 1984Hydrogen; Column length: 50. m; Column diameter: 0.32 mm; Program: not specified
CapillaryOV-11085.Ramsey and Flanagan, 1982Program: not specified

Normal alkane RI, polar column, custom temperature program

View large format table.

Column type Active phase I Reference Comment
CapillarySuperox 0.6; Carbowax 20M1400.Waggott and Davies, 1984Hydrogen; Column length: 50. m; Column diameter: 0.32 mm; Program: not specified
CapillaryCarbowax 400, Carbowax 20M, Carbowax 1540, Carbowax 4000, Superox 06, PEG 20M, etc.1400.Waggott and Davies, 1984Hydrogen; Column length: 50. m; Column diameter: 0.32 mm; Program: not specified

Lee's RI, non-polar column, temperature ramp

View large format table.

Column type Active phase I Reference Comment
CapillaryDB-5176.0Donnelly, Abdel-Hamid, et al., 199330. m/0.32 mm/0.25 μm, He, 40. C @ 3. min, 8. K/min, 285. C @ 29.5 min

References

Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, IR Spectrum, Vibrational and/or electronic energy levels, Gas Chromatography, Notes

Data compilation copyright by the U.S. Secretary of Commerce on behalf of the U.S.A. All rights reserved.

Chase, 1998
Chase, M.W., Jr., NIST-JANAF Themochemical Tables, Fourth Edition, J. Phys. Chem. Ref. Data, Monograph 9, 1998, 1-1951. [all data]

Manion, 2002
Manion, J.A., Evaluated Enthalpies of Formation of the Stable Closed Shell C1 and C2 Chlorinated Hydrocarbons, J. Phys. Chem. Ref. Data, 2002, 31, 1, 123-172, https://doi.org/10.1063/1.1420703 . [all data]

Puyo, Balesdent, et al., 1963
Puyo, J.; Balesdent, D.; Niclause, M.; Dzierzynski, M., Etude analytique et thermodynamique de la pyrolyse de l'hexachloroethane en phase gazeuse., Compt. Rend., 1963, 256, 3471-3473. [all data]

Cox and Pilcher, 1970
Cox, J.D.; Pilcher, G., Thermochemistry of Organic and Organometallic Compounds, Academic Press, New York, 1970, 1-636. [all data]

Lecat, 1927
Lecat, M., New binary azeotropes: 7th list, Ann. Soc. Sci. Bruxelles, Ser. B, 1927, 47, 108-14. [all data]

Lecat, 1926
Lecat, M., New binary azeotropes: 3rd list, Ann. Soc. Sci. Bruxelles, Ser. B, 1926, 45, 284-94. [all data]

Ivin and Dainton, 1947
Ivin, K.J.; Dainton, F.S., The vapour pressures, latent heats of sublimation and transition points of solid hexachloroethane, Trans. Faraday Soc., 1947, 43, 32. [all data]

Stephenson and Malanowski, 1987
Stephenson, Richard M.; Malanowski, Stanislaw, Handbook of the Thermodynamics of Organic Compounds, 1987, https://doi.org/10.1007/978-94-009-3173-2 . [all data]

Dykyj, 1970
Dykyj, J., Petrochemica, 1970, 10, 2, 51. [all data]

Stull, 1947
Stull, Daniel R., Vapor Pressure of Pure Substances. Organic and Inorganic Compounds, Ind. Eng. Chem., 1947, 39, 4, 517-540, https://doi.org/10.1021/ie50448a022 . [all data]

Lee, 1935
Lee, P.J.V.D., «65533»ber den Dampfdruck des Hexachlor«65533»thans, Z. Anorg. Allg. Chem., 1935, 223, 3, 213-216, https://doi.org/10.1002/zaac.19352230304 . [all data]

Nelson, 1930
Nelson, O.A., Vapor Pressures of Fumigants, Ind. Eng. Chem., 1930, 22, 9, 971-972, https://doi.org/10.1021/ie50249a020 . [all data]

Domalski and Hearing, 1996
Domalski, Eugene S.; Hearing, Elizabeth D., Heat Capacities and Entropies of Organic Compounds in the Condensed Phase. Volume III, J. Phys. Chem. Ref. Data, 1996, 25, 1, 1, https://doi.org/10.1063/1.555985 . [all data]

Murrill and Breed, 1970
Murrill, E.; Breed, L.W., Solid-solid phase transitions determined by differental scanning calorimetry Part II. Octahedral substances, Thermochim. Acta, 1970, 1, 409-414. [all data]

Petropavlov, Tsygankova, et al., 1988
Petropavlov, N.N.; Tsygankova, I.G.; Teslenko, L.A., Microcalorimetric investigation of polymorphic transitions in organic crystals, Sov. Phys. Crystallogr., 1988, 33(6), 853-855. [all data]

Rakhmenkulov, Gutov, et al., 1975
Rakhmenkulov, S.S.; Gutov, S.A.; Paukov, I.E., The heat capacity of hexachloroethane in the temperature range 13.7-360 K and the temperatures and enthalpies of its phase transition, Zhur. Fiz. Khim., 1975, 49, 2722. [all data]

Seki and Momotani, 1950
Seki, S.; Momotani, M., Heats of transition of hexachloroethane, Bull. Chem. Soc. Japan, 1950, 23, 30-31. [all data]

Gaines, Kay, et al., 1966
Gaines, A.F.; Kay, J.; Page, F.M., Determination of Electron Affinities. Part 8. - CCl4, CHCl3, and CH2Cl2, Trans. Farad. Soc., 1966, 62, 874, https://doi.org/10.1039/tf9666200874 . [all data]

Kimura, Katsumata, et al., 1981
Kimura, K.; Katsumata, S.; Achiba, Y.; Yamazaki, T.; Iwata, S., Ionization energies, Ab initio assignments, and valence electronic structure for 200 molecules in Handbook of HeI Photoelectron Spectra of Fundamental Organic Compounds, Japan Scientific Soc. Press, Tokyo, 1981. [all data]

Katsumata and Kimura, 1975
Katsumata, S.; Kimura, K., Photoelectron spectra and sum rule consideration. Effect of chlorine substitution on ionization energies for chloroethanes, chloroacetaldehydes and chloroacetyl chlorides, J. Electron Spectrosc. Relat. Phenom., 1975, 6, 309. [all data]

Shimanouchi, 1972
Shimanouchi, T., Tables of Molecular Vibrational Frequencies Consolidated Volume I, National Bureau of Standards, 1972, 1-160. [all data]

Castello and Gerbino, 1988
Castello, G.; Gerbino, T.C., Effect of Temperature on the Gas Chromatographic Separation of Halogenated Compounds on Polar and Non-Polar Stationary Phases, J. Chromatogr., 1988, 437, 33-45, https://doi.org/10.1016/S0021-9673(00)90369-8 . [all data]

White, Hackett, et al., 1992
White, C.M.; Hackett, J.; Anderson, R.R.; Kail, S.; Spock, P.S., Linear temperature programmed retention indices of gasoline range hydrocarbons and chlorinated hydrocarbons on cross-linked polydimethylsiloxane, J. Hi. Res. Chromatogr., 1992, 15, 2, 105-120, https://doi.org/10.1002/jhrc.1240150211 . [all data]

Zilka and Matucha, 1978
Zilka, L.; Matucha, M., Gas chromatographic analysis of chlorinated ethanes, J. Chromatogr., 1978, 148, 1, 229-235, https://doi.org/10.1016/S0021-9673(00)99342-7 . [all data]

Zenkevich, Eliseenkov, et al., 2011
Zenkevich, I.G.; Eliseenkov, E.V.; Kasatochkin, A.N.; Ukolov, A.I., Identification of the products of nonregioselective organic reactions by chromatography - mass spectrometry: chloro derivatives of dialkyl ethers, Rus. J. Anal. Chem., 2011, 66, 14, 1445-1454, https://doi.org/10.1134/S1061934811140218 . [all data]

Boatright and Crum, 1997
Boatright, W.L.; Crum, A.D., Nonpolar-volatile lipids from soy protein isolates and hexane-defatted flakes, J. Amer. Oil Chem. Soc., 1997, 74, 4, 461-467, https://doi.org/10.1007/s11746-997-0107-z . [all data]

Okumura, 1991
Okumura, T., retention indices of environmental chemicals on methyl silicone capillary column, Journal of Environmental Chemistry (Japan), 1991, 1, 2, 333-358, https://doi.org/10.5985/jec.1.333 . [all data]

Harland, Cumming, et al., 1986
Harland, B.J.; Cumming, R.I.; Gillings, E., The Kovats indexes of some organic micropollutants on an SE54 capillary column, EUR, I Org. Micropollut. Aquat. Environ., 1986, EUR 10388, 123-127. [all data]

Zenkevich, 2001
Zenkevich, I.G., Comparative Characterization of Conditions for Unambuguous Chromatographic Identification of Organic Compounds, Zh. Anal. Khim., 2001, 56, 9, 915-924. [all data]

Waggott and Davies, 1984
Waggott, A.; Davies, I.W., Identification of organic pollutants using linear temperature programmed retention indices (LTPRIs) - Part II, 1984, retrieved from http://dwi.defra.gov.uk/research/completed-research/reports/dwi0383.pdf. [all data]

Ramsey and Flanagan, 1982
Ramsey, J.D.; Flanagan, R.J., Detection and Identification of Volatile Organic Compounds in Blood by Headspace Gas Chromatography as an Aid to the Diagnosis of Solvent Abuse, J. Chromatogr., 1982, 240, 2, 423-444, https://doi.org/10.1016/S0021-9673(00)99622-5 . [all data]

Donnelly, Abdel-Hamid, et al., 1993
Donnelly, J.R.; Abdel-Hamid, M.S.; Jeter, J.L.; Gurka, D.F., Application of gas chromatographic retention properties to the identification of environmental contaminants, J. Chromatogr., 1993, 642, 1-2, 409-415, https://doi.org/10.1016/0021-9673(93)80106-I . [all data]


Notes

Go To: Top, Gas phase thermochemistry data, Phase change data, Gas phase ion energetics data, IR Spectrum, Vibrational and/or electronic energy levels, Gas Chromatography, References