A Tiny Treasury of Tessellations
Ernest R. Ranucci · Mathematics Teacher Learning and Teaching PK-12 · 1968
If a series of points on some region of a plane is connected by segments in groups of three, the portion of the plane selected may be considered to be completely covered by the triangular regions formed. The same portion could, of course, be covered by a different set of triangular regions (Figs. 1 and 2).