I am currently reading the paper
J. Bourgain, A. Gamburd, P. Sarnak, Generalizations of Selberg’s theorem and affine sieve, Acta Mathematica, 207 (2011), 255-290
and I noticed some problems with Section 3. Namely, there are two errors. The line “taking in (3.2)” is plainly wrong; since that would yield which is not desired. Further, equation (3.3) is wrong as stated; it should be .