Stupel, M. and Fraivert, D. (2015) “The properties of straight lines that issue from the point of intersection of the diagonals of a trapezoid, and are perpendicular to its sides”, Journal of Progressive Research in Mathematics, 5(4), pp. 618-623. Available at: http://scitecresearch.com/journals/index.php/jprm/article/view/437 (Accessed: 18May2024).