Cita APA (7a ed.)

Koper, E. (1993). The interstellar medium in M 31 and other nearby galaxies. Sterrewatcht.

Cita Chicago Style (17a ed.)

Koper, Enrico. The Interstellar Medium in M 31 and Other Nearby Galaxies. Leiden: Sterrewatcht, 1993.

Cita MLA (9a ed.)

Koper, Enrico. The Interstellar Medium in M 31 and Other Nearby Galaxies. Sterrewatcht, 1993.