30 in the newspaper world means end of story. That suggests showing the end of two of the Canadian publishers honoured in this blog.
The first is Export Publishing Enterprises Ltd who published 156 of their News Stand Library (NSL) imprint but the last one is 157. In common with just about everything else about Export the numbering of the NSL imprint is complicated. The first two books were unnumbered. Then books 3-95 were published except see the next paragraph. There is no 96-99. Then 100-157 but there are three sets of books published with the same number - 150, 151 and 152. So 157-4+3 = 156.
Two more complications. There is an unnumbered book, Better Your Bridge by Charles Platt, which is usually slotted between books 18 and 20 because there is no 19. There are also two numbers which I consider one. Both are the same book The Long November by James Benson Nablo. The first is "13 S" and the second is "R/15". Book 13 is another title. So 13 S is the first printing of The Long November. There is no number 15 and since Export usually designated a reprint with an "R" in front of the number, I believe R/15 is the second printing of The Long November. So the sequence is 13, 14, 13 S and R/15, 16, 17, 18, [19], 20 and so on. Maybe the the "5" in "15" was misread as an "S" during preparation of the book and somehow attached to "13". We'll never know.
After that lengthy introduction let's look at the last Export book which is The Private Life of a Street Girl! by James Clayford, a house pseudonym. Here the author is Albert Quandt. The NSL edition was published in January 1951. The book was first published as Ecstasy Novel 4 by Publishers Productions Inc. of New York in May 1950. The NSL edition's art by "WES" is tame compared to its Ecstasy Novel inspiration.
NSL 157
Ecstasy Novel 4
The last White Circle published by William Collins Sons & Co. Canada Ltd. was C.D. 545X in early 1952. However this was only the 459th book in the series. Numbers 73, 100, 119-199, 209, 212, 430 and 543 were not used - for a total of 87. And there are two books with number 527. So 545-87+1 = 459.
C.D. 545X was The Devil Man by Edgar Wallace, originally published in 1931 by Wm. Collins Sons & Co. of London. This was the second edition of the book in the White Circle imprint - the first was 255 in 1946. Both have uncredited art.
White Circle 255
White Circle C.D. 545X
The third major Canadian publisher, Harlequin, has not had a "30" yet.