In 2001 the American Mathematical Monthly published a paper on the Pythagorean theorem in n dimensions. (Unless you've seen this before, it doesn't say what you might imagine.) This prompted me to write up some work I had done back in the late 1960's on the subject. In doing the original work, I made use of an n dimensional analog of vector cross product, which I thought was not a known thing. It certainly is known now (click here), though I don't know when it was first conceived. At any rate, my paper is not publishable, but may be of sufficient novelty to be of interest to someone out there.