Genetic and environmental influences of daily and intra-individual variation in testosterone levels in middle-aged men - Panizzon, M S; Hauger, R; Jacobson, K C; Eaves, L J; York, T P; Prom-Wormley, E; Grant, M D; Lyons, M J; McKenzie, R; Mendoza, S P; Xian, H; Franz, C E; Kremen, W S (Psychoneuroendocrinology, 2013)