APA (7th ed.) Citation

Gunzert, R. (1960). Was ist Konzentration? Knapp.

Chicago Style (17th ed.) Citation

Gunzert, Rudolf. Was Ist Konzentration? Frankfurt am Main: Knapp, 1960.

MLA (9th ed.) Citation

Gunzert, Rudolf. Was Ist Konzentration? Knapp, 1960.

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