@article{YOSHIKAWAYukio:1999-05-01,
author="YOSHIKAWA, Yukio",
title="Open-ended Variety of Tessellation Made of Congruent Triangles : An Example of Open-ended Approach",
journal="Journal of Japan Society of Mathematical Education. Mathematical education",
ISSN="0021471X",
publisher="Japan Society of Mathematical Education",
year="1999",
month="may",
volume="81",
number="5",
pages="163-171",
URL="http://ci.nii.ac.jp/naid/110003729296/en/",
DOI="",
}