1. R.F. Post, Univ. of Califonria Radiat. Lab. Rep. U.C.R.L. 2209, 1953.
2. Higher zones of stability for the quadrupole mass filter
3. Das elektrische Massenfilter als Massenspektrometer und Isotopentrenner
4. Diplomarbeit;von Zahn,1956
5. W.M. Brubaker, 16th Annual Conf. Mass Spectrom., Pittsburgh, 1968 (not generally available).