An index to the Liverworts of the World. Vol. 12: Geissler, P. and H. Bischler: Racemigemma to Zoopsis. 1990. 337 p. gr8vo Cloth.

Contents: Racimigemma/ Radiania/ Radula/ Radulites/ Reboulia/Rectolejeunea/ Regredicaulis/ Reticulati-Sporites/ Rhacotheca/Rhakiocarpon/ Rhaphidolejeunea/ Rhizocaulia/ etc./ Ricciopsis/ Riccites/Riella/ Roemeria/ Roivainenia/ Rouseisporites/ Rudolphisporis/ Ruppinia/Ruttnerella/ Saccobasis/ Saccogyna/ Saccogynidium/ Salviatus/Salviniella/ Sandea/ Sarcocyphos/ Sarcomitrium/ Sauchia/ Sauteria/Saxosporis/ Scalius/ Scapania/ Scapaniella/ Scapanites/ Scaphophyllum/etc./ Scopulina/ Sedgwickia/ Sendtnera/ Sewardiella/ Shuklanites/ Simia/Simodon/ Sindonisce/ Siphonolejeunea/ etc./ Strozzia/ Strozzius/Stylolejeunea/ Sykorea/ Symbiezidium/ Symphyogyna/ Symphyomitra/Synhymenium/ etc./ Xenocephalozia/ Xenochila/ Xenothallus/ Zlivisporis/Zoopsidella/ Zoopsis.