APA-referens (7:e uppl.)

Pennsylvania Horticultural Society. Yearbook of the Pennsylvania Horticultural Society. Pennsylvania Horticultural Society.

Chicago-referens (17:e uppl.)

Pennsylvania Horticultural Society. Yearbook of the Pennsylvania Horticultural Society. Philadelphia, Pa.: Pennsylvania Horticultural Society.

MLA-referens (8:e uppl.)

Pennsylvania Horticultural Society. Yearbook of the Pennsylvania Horticultural Society. Pennsylvania Horticultural Society.

Varning: dessa hänvisningar är inte alltid fullständigt riktiga.