Galuskina I O , Lazic B , Armbruster T , Galuskin E V , Gazeev V M , Zadov A E , Pertsev N N , Jezak L , Wrzalik R , Gurbanov A G , American Mineralogist , 94 (2009) p.1361-1370, Kumtyubeite Ca5(SiO4)2F2 - A new calcium mineral of the humite group from, Northern Caucasus, Kabardino-Balkaria, Russia, Locality: Northern Caucasus, Kabardino-Balkaria, Russia