APA (7th ed.) Citation

Kniazev, A. Y., & Grebel, E. K. (2006). Planetary nebulae in the outer disk and Halo of M31. Planetary nebulae beyond the Milky Way.

Chicago Style (17th ed.) Citation

Kniazev, Alexei Y., and Eva K. Grebel. "Planetary Nebulae in the Outer Disk and Halo of M31." Planetary Nebulae Beyond the Milky Way 2006.

MLA (9th ed.) Citation

Kniazev, Alexei Y., and Eva K. Grebel. "Planetary Nebulae in the Outer Disk and Halo of M31." Planetary Nebulae Beyond the Milky Way, 2006.

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