A comment on "Estimating the standard deviation from extreme Gaussian values"

This letter relates to a paper (Stark and Brankov, IEEE Signal Process. Lett., vol.11, no.3, p.320-2, March 2004) that used extreme Gaussian values to estimate the standard deviation. We show that the estimator given in the aforementioned paper is a special case of relevant ones previously obtained in the literature about which the authors are unaware. Also, some slight errors in the paper are pointed out and corrected.