Kreiner, J.M. Zola, S. Ogloza, W. Pokrzywka, B. Drozdz, M. Stachowski, G. Zakrzewski, B. Niarchos, P.G. Gazeas, K. Rucinski, S.M. Siwak, M. Koziel, D. Kjurkchieva, D. Marchev, D., The W UMa-type stars program: First results, current status and perspectives, Astrophysics and Space Science, (304), 71-73, 2006, 0004-640X, 1572-946X