References for Solanaceae
Goodspeed, T.H. 1945. Studies in Nicotiana III. A taxonomic organization of the genus. Univ. Calif. Publ. Bot. 18:335-344.
Stebbins, G.L., Jr., and E.F. Paddock. 1949. The Solanum nigrum complex in Pacific North America. Madrono 10:70-81.
Waterfall, U.T. 1958. A taxonomic study of the genus Physalis in North America north of Mexico. Rhodora 60:107-114, 128-142, 152-173.

Source for the Reference Lists

George W. Douglas, Del Meidinger and Jim Pojar. 1998-2002. Illustrated Flora of British Columbia.