[1] V. A. Ambartsumian Byurakan Astrophysical Observatory,Groupe d’Astrophysique
[2] Hamburger Sternwarte,Astrophysicalisces Institut
[3] CNRS & University de Montpellier,INAF
[4] Universität Jena,undefined
[5] Universita di Roma “La Sapienza”,undefined
[6] Osservatorio Astronomico Bologna,undefined