APA (7th ed.) Citation

Penston, M., Appenzeller, I., & Wagner, S. (1990). The extended narrow line region of NGC 4151: I. emission line ratios and their implications. Astronomy and astrophysics, 236(1), .

Chicago Style (17th ed.) Citation

Penston, Margaret, Immo Appenzeller, and Stefan Wagner. "The Extended Narrow Line Region of NGC 4151: I. Emission Line Ratios and Their Implications." Astronomy and Astrophysics 236, no. 1 (1990).

MLA (9th ed.) Citation

Penston, Margaret, et al. "The Extended Narrow Line Region of NGC 4151: I. Emission Line Ratios and Their Implications." Astronomy and Astrophysics, vol. 236, no. 1, 1990.