Look at this http://spazioscuola.altervista.org/U...samplingAR.htm
An excerpt:

A STORY ABOUT UNDERSAMPLING

by Angelo Ricotta - Rome, Italy



ITALIAN VERSION

In the article "Turning Nyquist upside down by undersampling" by Bonnie Baker, EDN 12 May 2005, are reported two formulae to compute an allowable sampling frequency for undersampling a bandpass signal. I was surprised by that because I have been using the undersampling technique since the late seventies and even wrote a report (Angelo Ricotta, "Some remarks on the sampling and processing of SODAR data", Technical Report, IFA-CNR, July 1983) where I gave two simple and practical formulae to compute all the allowable sampling frequencies for undersampling a given bandpass signal. The report was written in Italian and was known, at least, among the Italian community working on SODAR systems in which a few people and even students utilized my formulae in an unfair way because they did not mention the source. On 10 October and 7 December 1991, also to stop the above misuses, I sent two letters, containing my formulae for undersampling, to EDN Signals & Noise Editor but I never received an answer...