Cita APA (7th ed.)

Cumpa, J., & Tegtmeier, E. (2011). Ontological categories. Ontos Verlag.

Cita Chicago (17th ed.)

Cumpa, Javier, i Erwin Tegtmeier. Ontological Categories. Frankfurt: Ontos Verlag, 2011.

Cita MLA (9th ed.)

Cumpa, Javier, i Erwin Tegtmeier. Ontological Categories. Ontos Verlag, 2011.