Kotte, H. , Ambatipudi, R. , Bertilsson, D.. "A ZVS Flyback DC-DC Converter using Multilayered Coreless Printed-Circuit Board(PCB) Step-down Power Transformer". World Academy of Science, Engineering and Technology, Open Science Index 46, International Journal of Electronics and Communication Engineering, (2010), 4(10), 1446 - 1453.