Cita APA (7a ed.)

Amster, P., Haddad, J., Ortega, R., & Ureña, A. Periodic motions in forced problems of Kepler type.

Cita Chicago Style (17a ed.)

Amster, P., J. Haddad, R. Ortega, y A.J Ureña. Periodic Motions in Forced Problems of Kepler Type.

Cita MLA (8a ed.)

Amster, P., et al. Periodic Motions in Forced Problems of Kepler Type.