Ramamurthy, S., S. Ramaswamy, S. Thirunavukarasu, and D. Sujithsivarajan. “Management of Maxillary Midline Diastema in Early Mixed Dentition by 2×2 Appliance”. Pakistan Orthodontic Journal, vol. 3, no. 2, Dec. 2011, pp. 65-68, https://www.poj.org.pk/index.php/poj/article/view/52.