1. “Multicollinearity and Nonadditive Regression Models,”;Althauser,1971
2. “Four-Variable Causal Models and Partial Correlations.”;Blalock;American Journal of Sociology,1962
3. Causal Inferences in Nonexperimental Research;Blalock,1964
4. “Theory Building and Causal Inferences”;Blalock,1968
5. Causal Models in the Social Sciences;Blalock,1971