| Zalman Usiskin and Jennifer Griffin, "The Classification of Quadrilaterals | |
|---|---|
| A Study of Definition", Information Age Publishing, 2008, pp | with interactive animation illustrating a rectangle that becomes a 'crossed rectangle', making a good case for regarding a 'crossed rectangle' as a type of rectangle |
Owen Byer; Felix Lazebnik; Deirdre L.
13.
22.
14