Rudd (1979)
Rudd, Andrew. "Divestment of South African Equities: How Risky?" Journal of Portfolio Management, Fall 1979.
From the paper: "The effect on portfolio risk of excluding the companies operating in South Africa ... is, contrary to intuition, not particularly important."
LK comment: Strong and important early study treating the problem of South Africa divestment from a multifactor risk management perspective. See also Rudd (1981).
Link: http://jpm.iijournals.com/content/5/3/5