Cita APA (7th ed.)

Grabau, A. W. (1922). Ordovician fossils of north China. Geological Survey of China.

Cita Chicago (17th ed.)

Grabau, Amadeus W. Ordovician Fossils of North China. Peking: Geological Survey of China, 1922.

Cita MLA (8th ed.)

Grabau, Amadeus W. Ordovician Fossils of North China. Geological Survey of China, 1922.