E. V. Glushkova, M. V. Zabolotskikh, S. E. Koposov, O. I. Spiridonova, V. V. Vlasyuk: Photometry of the poorly studied galactic open star clusters King 13, King 18, King 19, King 20, NGC 136, and NGC 7245. In: Astronomy Letters. Band36, Nr.1, Januar 2010, ISSN1063-7737, S.14–26, doi:10.1134/S1063773710010032 (springer.com [abgerufen am 1. Oktober 2021]).
E. V. Glushkova, M. V. Zabolotskikh, S. E. Koposov, O. I. Spiridonova, V. V. Vlasyuk: Photometry of the poorly studied galactic open star clusters King 13, King 18, King 19, King 20, NGC 136, and NGC 7245. In: Astronomy Letters. Band36, Nr.1, Januar 2010, ISSN1063-7737, S.14–26, doi:10.1134/S1063773710010032 (springer.com [abgerufen am 1. Oktober 2021]).
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E. V. Glushkova, M. V. Zabolotskikh, S. E. Koposov, O. I. Spiridonova, V. V. Vlasyuk: Photometry of the poorly studied galactic open star clusters King 13, King 18, King 19, King 20, NGC 136, and NGC 7245. In: Astronomy Letters. Band36, Nr.1, Januar 2010, ISSN1063-7737, S.14–26, doi:10.1134/S1063773710010032 (springer.com [abgerufen am 1. Oktober 2021]).