Solution idea seen here: https://justpuzzles.wordpress.com/2019/07/05/bongard-problem-36-2.
Adjacent-numbered pages: BP1081 BP1082 BP1083 BP1084 BP1085  *  BP1087 BP1088 BP1089 BP1090 BP1091
nice, rotate, stretch, left-narrow, traditional
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Teun Spaans