“A LICHNEROWICZ-TYPE RESULT ON A SEVEN-DIMENSIONAL QUATERNIONIC CONTACT MANIFOLD” (2013) Annual of Sofia University St. Kliment Ohridski. Faculty of Mathematics and Informatics, 101, pp. 193–213. Available at: https://annual.uni-sofia.bg/index.php/fmi/article/view/239 (Accessed: 15 December 2025).