² See also Anderson and Nilsson (1964); Carroll and Taylor (1968); Flanagan (1951, 1954); Hemphill (1959); Kay and Meyer (1962); Lau, Newman, and Broedling (1980); Lau and Pavett (1980); O’Neill and Kubany (1957); McCall, Morrison, and Hanman (1978); Pavett and Lau (1983); Shartle (1956); and P. A. Stewart (1967).