re Pulsational theory including closely spaced frequencies. Recently Lazlo Kiss and others made availabe online a couple of preprints on these sorts of topics with special reference to particular LPVs. I can't remember all the details, but I'm sure they decided a couple of semiregulars had beat effects in their long term lightcurves due to very close periods. Trouble is, I can't remember which stars either. Lazlo used to be on one of the vsnet lists, but he's probably busy and missed these posts. So, I suggest you go to http://xxx.soton.ac.uk/find/astro-ph and use the search routines there to search on papers with "Kiss" as one of the authors over the past year or so. You should find a couple of papers on LPVs that are marked "I" and "II" [ie 1 and 2 in roman numerals] in their titles. There are links to these preprints that allow you to download them as postscript or pdf files. One of these papers will be of great interest to you. Let me know if you get really stuck and can't find them or can't get this search engine to work and I'll try and dig them out myself. The above URL is the UK mirror for these preprints... ...I believe the master one is xxx.lanl.edu or similar in the US, and there is also an Italian mirror, a Japanese mirror, and probably many more. A daily look at http://xxx.soton.ac.uk/list/astro-ph/recent can lead to some interesting papers, such as the two on the "Faint Sky Variability Survey" that cropped up yesterday. Implications re a future ability to observe outburst object rise time behaviour from faint precursor states for the covered fields are evident??????possibly... Ironically, as all these preprint papers are not yet published, and as the ADS service holdings often end around 1996, the years 1996-1998 can be the hardest years to get papers for online! Although some will still survive in preprint form at astro-ph. Finally, so as not to mislead, I note that not every paper going is presented to astro-ph... ...it seems to be based on voluntary contributions from authors, and possibly not all journals allow this. Cheers John