When I was interested in “survival” type topics back in the 80’s, there were a few magazines devoted to the topic, and I remember an ad for a large collection/l

When I was interested in “survival” type topics back in the 80’s, there were a few magazines devoted to the topic, and I remember an ad for a large collection/library of useful basic information (how to make soap, butcher an animal, etc.) all placed on microfilm cards and came with a simple mechanical magnifier/reader. No power or fancy tech required.