Walker, E. M., & Fox, W. S. (1946). Field birch in Ontario (Betula populifolia Marsh.). Zenodo.
Cita Chicago (17th ed.)Walker, E. M., i W. Sherwood Fox. Field Birch in Ontario (Betula Populifolia Marsh.). Zenodo, 1946.
Cita MLA (9th ed.)Walker, E. M., i W. Sherwood Fox. Field Birch in Ontario (Betula Populifolia Marsh.). Zenodo, 1946.
Atenció: Aquestes cites poden no estar 100% correctes.