APA (7th ed.) Citation

Katharina, v. S. (2007). The letters of Catherine of Siena. The letters of Catherine of Siena.

Chicago Style (17th ed.) Citation

Katharina, von Siena. "The Letters of Catherine of Siena." The Letters of Catherine of Siena 2007.

MLA (8th ed.) Citation

Katharina, von Siena. "The Letters of Catherine of Siena." The Letters of Catherine of Siena, 2007.

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