APA (7th ed.) Citation

Schumann, R., & Storck, K. (1971). The letters of Robert Schumann. B. Blom.

Chicago Style (17th ed.) Citation

Schumann, Robert, and Karl Storck. The Letters of Robert Schumann. [New York]: B. Blom, 1971.

MLA (9th ed.) Citation

Schumann, Robert, and Karl Storck. The Letters of Robert Schumann. B. Blom, 1971.