WILLz learned of NPL summer 1972 when he found Enigmas in Library of Congress while interning for his Congressman. He joined at end of summer when he returned home.
Source: email from Munro.
[WILLz' nom is a rubric for his name: Will, short Z].
There's not a lot I can add to the origin of my nom–except that it was Nightowl's suggestion. I liked it and immediately accepted it. Nightowl was the editor when I joined in '72.