Dyfyniad APA

Hurd, P. D. (1961). Biological education in American secondary schools 1890-1960. American Institute of Biological Sciences.

Dyfyniad Arddull Chicago

Hurd, Paul Dehart. Biological Education in American Secondary Schools 1890-1960. Washington, DC: American Institute of Biological Sciences, 1961.

Dyfyniad MLA

Hurd, Paul Dehart. Biological Education in American Secondary Schools 1890-1960. American Institute of Biological Sciences, 1961.

Rhybudd: Mae'n bosib nad yw'r dyfyniadau hyn bob amser yn 100% cywir.