Is the apparent redshift cut-off in the Tololo deep survey real

For several years it was thought that a cut-off in the space distribution of high-redshift QSOs might have been observed well below redshift 3. It is now known that QSOs of redshift z is approximately 3 are not, after all, too hard to find. Much of the difficulty was related to selection effects in the earlier surveys. Comparisons between redshift distributions from the Tololo deep survey and from some illustrative models show that there is no evidence for any redshift cut-off. (author)