MLA

Hansen, George. The Orchid Hybrids. London: Dulau & co.; [etc., etc.], 1895.

APA

Hansen, G. (1895). The orchid hybrids. London: Dulau & co.; [etc., etc.].

Chicago

Hansen, George, The Orchid Hybrids. London: Dulau & co.; [etc., etc.], 1895.