There are several different periodicals that specialize in series book information. One of the oldest is the Yellowback Library. I am not sure how many years it has been published, but Gil O'Gara does a great job giving us a monthly periodical about our hobby. The banner reads, "Series Books, Dime Novels, and related literature." There is often a reprint of some kind, normally of the Dime Novel variety, and there have been several articles over the last year that feature information on such series as Rick Brant, Ken Holt, the Oz books, and other assorted series.
The periodical runs approximately 26 pages long, and includes some regular advertisers that specialize in series books. A one year subscription runs 36.00. You can send a check to Gil O'Gara, PO Box 36172, Des Moines, IA 50315. You can email Gil at firstname.lastname@example.org .
For juvenile series book information, Yellowback Library is worth a look!!