APA

Sommerfeld A., . (1949). Lectures on theoretical physics. New York: Academic Press.

Chicago

Sommerfeld Arnold, . 1949. Lectures on theoretical physics. New York: Academic Press.

Harvard

Sommerfeld A., . (1949). Lectures on theoretical physics. New York: Academic Press.

MLA

Sommerfeld Arnold, . Lectures on theoretical physics. New York: Academic Press. 1949.