Khoshnoudirad, Daniel. “A Further Study for the Upper Bound of the Cardinality of Farey Vertices and Application in Discrete Geometry”. Journal of Algebra Combinatorics Discrete Structures and Applications, vol. 2, no. 3, Sept. 2015, pp. 169-90, https://www.jacodesmath.com/index.php/jacodesmath/article/view/21.