Cita APA (7a ed.)

Amster, P., & Haddad, J. On existence of periodic solutions for kepler type problems.

Cita Chicago Style (17a ed.)

Amster, P., y J. Haddad. On Existence of Periodic Solutions for Kepler Type Problems.

Cita MLA (8a ed.)

Amster, P., y J. Haddad. On Existence of Periodic Solutions for Kepler Type Problems.