APA (7th ed.) Citation

Elena, A. (1983). On the different kinds of attractive forces in Kepler.

Chicago Style (17th ed.) Citation

Elena, Alberto. On the Different Kinds of Attractive Forces in Kepler. 1983.

MLA (9th ed.) Citation

Elena, Alberto. On the Different Kinds of Attractive Forces in Kepler. 1983.

Warning: These citations may not always be 100% accurate.