All examples in this Problem are outlines of shapes or solid black shapes.
M. M. Bongard, Pattern Recognition, Spartan Books, 1970, p. 215.
BP136 is the same solution (flipped) but with only polygonal outlines and also with extraneous dots distracting from the solution.
Adjacent-numbered pages: BP1 BP2 BP3  *  BP5 BP6 BP7 BP8 BP9