Alexander von Humboldt. (2007). Jahresbericht-Annual Report 2007. Himboldt-foundation.
Cita Chicago (17th ed.)Alexander von Humboldt. Jahresbericht-Annual Report 2007. Bonn: Himboldt-foundation, 2007.
Cita MLA (9th ed.)Alexander von Humboldt. Jahresbericht-Annual Report 2007. Himboldt-foundation, 2007.
Atenció: Aquestes cites poden no estar 100% correctes.