Hagberg M (1981). "Muscular endurance and surface electromyogram in isometric and dynamic exercise". Journal of Applied Physiology. 51 (1): 1–7. doi:10.1152/jappl.1981.51.1.1. PMID7263402.
Van Dongen HP (2006). "Shift work and inter-individual differences in sleep and sleepiness". Chronobiol. Int. 23 (6): 1139–47. doi:10.1080/07420520601100971. PMID17190701.
Hagberg M (1981). "Muscular endurance and surface electromyogram in isometric and dynamic exercise". Journal of Applied Physiology. 51 (1): 1–7. doi:10.1152/jappl.1981.51.1.1. PMID7263402.
Van Dongen HP (2006). "Shift work and inter-individual differences in sleep and sleepiness". Chronobiol. Int. 23 (6): 1139–47. doi:10.1080/07420520601100971. PMID17190701.