APA (7th ed.) Citation

Leo IV ... (1881). Opera omnia. [Verlag nicht ermittelbar].

Chicago Style (17th ed.) Citation

Leo IV ... Opera Omnia. Parisiis: [Verlag nicht ermittelbar], 1881.

MLA (9th ed.) Citation

Leo IV ... Opera Omnia. [Verlag nicht ermittelbar], 1881.

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