APA (7th ed.) Citation

Poppinga, O. H. (1977). Ostfriesland.

Chicago Style (17th ed.) Citation

Poppinga, Onno Hans. Ostfriesland. 1977.

MLA (9th ed.) Citation

Poppinga, Onno Hans. Ostfriesland. 1977.

Warning: These citations may not always be 100% accurate.