2015 | Serum 25-hydroxyvitamin D levels and testosterone deficiency in middle-aged Korean men: a cross-sectional study | 김상수; Young Jin Tak; Jeong Gyu Lee; Yun Jin Kim; Nam Cheol Park; Sang Soo Kim; Sangyeoup Lee; Byung Mann Cho; Eun Hee Kong; Dong Wook Jung; Yu Hyeon Yi |