Data from Barnes & Noble
The copyright page does not explicitly list "Barnes & Noble Books", and does say "For information address HarperCollins Children's Books ... Reprinted by permission of HarperCollins Publishers", so several sources incorrectly list the publisher as HarperCollins. WorldCat and Barnes & Noble (of course) properly credit it to "Barnes & Noble Books".
Since no publication date is stated, some sources incorrectly give the 1972 or 1982, i.e. the copyright and first publication years of the first and last novels in the omnibus (and long before the creation of HarperCollins).
Probably the novels are paginated separately, rather than the omnibus numbered to p540 or 541.
WorldCat library record OCLC 824609771 (as "[200?]") states "1 v. (various pagings)" and OCLC 868154079 (as 1972 HarperCollins!) reports 185 pp, probably from the last page of the first or last novel.
