Zhang, Yuling, Xi Wang, Ye Liu, Hui Qu, Shuqiang Qu, Wei Wang, and Lihong Ren. 2012. “The GC, CYP2R1 and DHCR7 Genes Are Associated With Vitamin D Levels in Northeastern Han Chinese Children”. Swiss Medical Weekly 142 (2930):w13636. https://doi.org/10.4414/smw.2012.13636.