On the last page of Selberg's 1972 paper "Remarks on sieves' (item #37 in the list of publications), reference is made to a large sieve inequality for pseudocharacters and its application to density-type estimates for zeros of Dirichlet L-series.

The first file below, dating from around 1970, appears to be a set of Selberg's working notes from a lecture on this topic. File 2 shows some additional pages from the same manila folder found on the shelves next to Selberg's desk. The third file is a scan of the relevant pages from item 37.