Study of periodicities of the DAV white dwarf G 117-B15A with the Whole Earth Telescope oleh Kepler S.O., Winget D.E., Nather R.E., Bradley P.A., Robinson E.L., Grauer A.D., Fontaine G., Bergeron P., Vauclair G., Claver C.F., Marar T.M.K., Seetha S., Ashoka B.N., Mazeh T., Leibowitz E.M., Dolez N., Chevreton M., Barstow M.A., Clemens J.C., Kleinman S.J., Sansom A.E., Tweedy R.W., Kanaan A., Hine B.P., Provencal J.L., Wood M.A., Wesemael F., Solheim J.-E., Emanuelsen P.-I.