W1968 World Championship Tennis circuitW1969 World Championship Tennis circuitW1971 World Championship Tennis circuitW1972 World Championship Tennis circuitW1973 World Championship Tennis circuitW1974 World Championship Tennis circuitW1975 World Championship Tennis circuitW1976 World Championship Tennis circuitW1977 World Championship Tennis circuitW1982 World Championship Tennis circuitW1983 World Championship Tennis circuitW1984 World Championship Tennis circuit