Garman, Mark B. and Michael J. Klass, "On the Estimation of Security Price Volatilities from Historical Data", Journal of Business, Vol. 53, No. 1, (January 1980), pp. 67-78.
Abstract: Improved estimators of security price volatilities are formulated. These estimators employ data of the type commonly found in the financial pages of a newspaper: the high, low, opening, and closing prices and the transaction volume. The new estimators are seen to have relative efficiencies that are considerably higher than the standard estimators.