APA (7th ed.) Citation

Krüger, E. (1937). Die Porta Nigra in Trier (6. Aufl.).

Chicago Style (17th ed.) Citation

Krüger, Emil. Die Porta Nigra in Trier. 6. Aufl. Trier, 1937.

MLA (9th ed.) Citation

Krüger, Emil. Die Porta Nigra in Trier. 6. Aufl. 1937.

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