from Fancyclopedia 2 ca. 1959 and Fancyclopedia 1 ca. 1944
Subzine publishers ordinarily announce that they are willing to trade on an even basis (all my issues for all your issues) with other regularly-appearing fanzines. And many will send each monthly or bimonthly issue faithfully, when the other editor only turns out one or two little ratty issues a year. Complications occur when one fan publishes more than one good-sized periodical, or when more than one share equally in the work of putting out a fanzine and each wants a copy of exchanged pubs for his collection. The solution to much of the exchange problem is FAPA.