Cita APA (7a ed.)

Den Boer, A. F. (1959). Ornamental crab apples. American Association of Nurserymen.

Cita Chicago Style (17a ed.)

Den Boer, Arie F. Ornamental Crab Apples. Washington: American Association of Nurserymen, 1959.

Cita MLA (8a ed.)

Den Boer, Arie F. Ornamental Crab Apples. American Association of Nurserymen, 1959.