Paper folding and cutting; a series of foldings and cuttings especially adapted to kindergartens and public schools (1892)
Ball, Katherine M · Boston, The Prang educational company · leaf 36
THE TREFOIL. Fold to Fig. 4, and cutfrom I to 2. The arc 4-1should be a quadrant, with 3as centre. The line 2-4-1must be at right angles with5-0. … 30 PAPER FOLDING AND CUTTING.
Paper work
Internet Archive · Library of Congress · Public Domain Mark 1.0. Free to use for anything.