2542 20160701171707.0 ASTROimport-699 Schoenaers, C. 2004 Direct detection of multiple periods in variable stars In some observational data sets of variable stars, multiperiodicity was not always recognized as such, and only became apparent when other observational material became available. In other cases, consecutive prewhitening starting with the obviously most significant frequency could lead to a wrong multifrequency solution. A few examples illustrating this are given. Searching directly for a multifrequency solution can often remedy this. Examples are given and the results of applying this technique to a large set of Hipparcos photometric data are communicated. An overview of the multiple periodicities found in ß Cephei stars and SPB stars is reported in detail. Cuypers, J. IAU Colloq. 193: Variable Stars in the Local Group 310 2004 283 http://esoads.eso.org/abs/2004ASPC..310..283S published in NONREF