Lusso, Elisabeta, Fumagalli, Michele, Rafelski, Marc, Neeleman, Marcel, Prochaska, Jason X., Hennawi, Joseph F., O’Meara, John M., Theuns, Tom, "The Spectral and Environment Properties of z ∼ 2.0–2.5 Quasar Pairs", Astrophysical Journal, 2018