Zibetti, S., Ménard, B., Nestor, D. B., Quider, A. M., Rao, S. M., & Turnshek, D. A. (2007). Optical properties and spatial distribution of Mg II absorbers from SDSS image stacking. Astrophysical Journal, 658(1 Part 1), 161-184. doi:10.1086/511300.