Jan Thomas is the author of The Genus Morinda (Morindeae, Rubioideae, Rubiaceae) in New Caledonia (1994), Pollen Morphology in Psychotria (Rubiaceae, Rubioideae, Psychotrieae) and Its Taxonomic Significance (1992), Biographical Index of South Australians, 1836-1885 (1988), Revision of the Genus Prismatomeris Thw. (Rubiaceae, Morindeae) (1987), Helping with Mathematics (1984).