This site now hosts a complete archive of PDF versions of The Problemist Supplement, from 1992 to the current year. This magazine is aimed mainly at newcomers to chess composition, so it is recommended for those who want to find out more about chess problems. You can find the archive here.
Reason for choice: A remarkable early helpmate by an outstanding but sadly little remembered Finnish composer. At the time of its publication only about half a dozen sound original helpmates had as yet appeared in the magazine. It is remarkable not only for its elegance but because it uses the twinning form, which only much later came into prominence. People are still publishing originals like this even nowadays.