Fiddner, Peter. "Is it a trapezoid or a parallelogram?". OER Commons. Institute for the Study of Knowledge Management in Education, 12 Feb. 2016. Web. 27 Dec. 2024. <https://oercommons.org/authoring/12087-is-it-a-trapezoid-or-a-parallelogram>.
Fiddner, P. (2016, February 12). Is it a trapezoid or a parallelogram?. OER Commons. Retrieved December 27, 2024, from https://oercommons.org/authoring/12087-is-it-a-trapezoid-or-a-parallelogram.