Samoilenko YS, Strilets OV. On simple $n$-tuples of subspaces of a Hilbert space. Ukr. Mat. Zhurn. [Internet]. 2009Dec.25 [cited 2024Apr.19];61(12):1668-703. Available from: https://umj.imath.kiev.ua/index.php/umj/article/view/3130