Gray, S.F. 1821. A natural arrangement of British plants, according to their relations to each other, as pointed out by Jussieu, De Candolle, Brown, &c. including those cultivated for use; with an introduction to botany, in which the terms newly introduced are explained; illustrated by figures. 1: i–xxviii, 1–824, pls. I–XXI. BHLReference page.