Richer, M. G., S. h. Báez, and J. A. López. 2010. “What Can We Learn About the Kinematics of Bright Extragalactic Planetary Nebulae?”. Revista Mexicana De Astronomía Y Astrofísica 45 (2). https://revistas.unam.mx/index.php/revmexaa/article/view/20676.