Cita APA (7th ed.)
Fenchel, W., Nielsen, J., & Schmidt, A. L. (2003). Discontinuous groups of isometries in the hyperbolic plane. Walter de Gruyter.
Cita Chicago (17th ed.)
Fenchel, W., Jakob Nielsen, i Asmus L. Schmidt. Discontinuous Groups of Isometries in the Hyperbolic Plane. Berlin ; New York: Walter de Gruyter, 2003.
Cita MLA (9th ed.)
Fenchel, W., et al. Discontinuous Groups of Isometries in the Hyperbolic Plane. Walter de Gruyter, 2003.
Atenció: Aquestes cites poden no estar 100% correctes.