Banaru, M. “ON THE GRAY-HERVELLA CLASSES OF AH-STRUCTURES ON SIX-DIMENSIONAL SUBMANIFOLDS OF CAYLEY ALGEBRA”. Ann. Sofia Univ. Fac. Math. And Inf., vol. 95, Dec. 2003, pp. 125-31, https://stipendii.uni-sofia.bg/index.php/fmi/article/view/182.