Cooper et al. (1976), Day (1981), de Witt et al. (1994), Hockey (1993), Hockey and Hockey (1980), Hockey and Velasquez (1992), Hockey et al. (1992), Kalejta (1991, 1992a,b,c), Kalejta and Hockey (1994), Little (1993), Summers et al. (1977), Turpie (1995), van Wyk (1983), Velasquez (1992, 1993), Velasquez and Hockey (1992), Velasquez et al. (1991).
