APA (7th ed.) Citation

Mahr, G., & Guardini, R. (1976). Romano Guardini. Köpfe des XX. Jahrhunderts.

Chicago Style (17th ed.) Citation

Mahr, Gerhard, and Romano Guardini. "Romano Guardini." Köpfe Des XX. Jahrhunderts 1976.

MLA (8th ed.) Citation

Mahr, Gerhard, and Romano Guardini. "Romano Guardini." Köpfe Des XX. Jahrhunderts, 1976.

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