Today’s Saturday Stumper

Today’s Saturday Stumper, by Lester Ruff, was a challenge. It helped to know stuff — “Bart’s first words” (2-Down, nine letters). A known known. Other stuff — “Calvin Coolidge, by birth” (3-Down, nine letters) — known unknowns. O epistemology. For me, the puzzle was solvable only with a good deal of help from crossings.

Four clues that I especially liked: 1-Across, eight letters: “Probationer’s problem, perhaps.” 37-Across, ten letters: “18+ points, to librarians.” 42-Across, eight letters: “Paper that requires reporting.” And 1-Down, nine letters, a blast from TV past: “’90s diet with menu cards.” No spoilers: the answers are in the comments.