R. Rangarajan, P. Shashikala, and C. K. Honnegowda. “Certain Combinatorial Properties of Twin Triplets Related to Tchebychev Polynomials”. International Journal of Mathematics And Its Applications, vol. 4, no. 4, Dec. 2016, pp. 1-10, https://ijmaa.in/index.php/ijmaa/article/view/949.