| Owen Byer, Felix Lazebnik and Deirdre Smeltzer, Methods for Euclidean Geometry, Mathematical Association of America, 2010, pp | Zalman Usiskin and Jennifer Griffin, "The Classification of Quadrilaterals |
|---|---|
| Note: 's original definition and some English dictionaries' definition of rhombus excludes squares, but modern mathematicians prefer the inclusive definition |
A Study of Definition", Information Age Publishing, 2008, pp.
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