Pérez-Villegas, A. Optical and Interpretative Astronomy, MPI for Extraterrestrial Physics, Max Planck Society;
Pérez-Villegas, A., Pichardo, B., & Moreno, E. (2015). Stellar orbital studies in normal spiral galaxies - II. Restrictions on structural and dynamical parameters on spiral arms. The Astrophysical Journal, 809(2): 170, pp. 1-27. doi:10.1088/0004-637X/809/2/170.