“…Forty studies [27–42,45,48–55,57,58,60,63–67,69–73] compared eLearning to traditional learning and 9 studies [43,44,46,47,56,59,61,62,68] compared one mode to another mode of eLearning. The shortest duration of exposure was 20 minutes [47] and the longest was 1 year [58].…”