The horn book magazine.
APA Citation
Mahony, B. E., Bookshop for Boys and Girls (Boston, M. The horn book magazine. [Boston: Horn Book, inc., etc.].
MLA Citation
Mahony, Bertha E, and Mass.) Bookshop for Boys and Girls (Boston. The Horn Book Magazine. [Boston: Horn Book, inc., etc.],
Warning: These citations may not always be complete (especially for serials).