− | http://ac.els-cdn.com/S1877042810022007/1-s2.0-S1877042810022007-main.pdf?_tid=163e5b14-f97d-11e6-9cc8-00000aab0f02&acdnat=1487822812_de9589e860a84d8cce36723ca99f82ee | + | [http://ac.els-cdn.com/S1877042810022007/1-s2.0-S1877042810022007-main.pdf?_tid=163e5b14-f97d-11e6-9cc8-00000aab0f02&acdnat=1487822812_de9589e860a84d8cce36723ca99f82ee A Document of Effects of Geogebra] |