Cita APA (7a ed.)

Walén, C. (1944). On the theory of sun-spots. Almquist & Wiksels.

Cita Chicago Style (17a ed.)

Walén, Claës. On the Theory of Sun-spots. Uppsala, Sweden: Almquist & Wiksels, 1944.

Cita MLA (8a ed.)

Walén, Claës. On the Theory of Sun-spots. Almquist & Wiksels, 1944.