Gray's manual of botany :
a handbook of the flowering plants and ferns of the central and northeastern United States and adjacent Canada.
APA Citation
Gray, A., Fernald, M. Lyndon. (1950). Gray's manual of botany: a handbook of the flowering plants and ferns of the central and northeastern United States and adjacent Canada. 8th (centennial) ed., Portland, Or.: Dioscorides Press.
MLA Citation
Gray, Asa, 1810-1888, and Merritt Lyndon Fernald. Gray's Manual of Botany: a Handbook of the Flowering Plants And Ferns of the Central And Northeastern United States And Adjacent Canada. 8th (centennial) ed., Portland, Or.: Dioscorides Press, 1950.
Warning: These citations may not always be complete (especially for serials).