Prochaska, J., O'Meara, J., Fumagalli, M., Bernstein, R., & Burles, S. (2015). The Keck + Magellan Survey for Lyman Limit Absorption. III. Sample Definition and Column Density Measurements. Astrophysical Journal Supplement, 221(1), https://doi.org/10.1088/0067-0049/221/1/2