You may also wish to search for items by Letham, D. and Letham.
Only one matching reference was found.
Badenoch-Jones, J.; Summons, R.E.; Entsch, B.; Rolfe, B.G.; Parker, C.W.; Letham, D.S., Mass spectrometric identification of indole compounds produced by Rhizobium strains, Biomed. Mass Spectrom., 1982, 9, 10, 429-437, https://doi.org/10.1002/bms.1200091005 . [all data]