“…Another type of principal subspaces, called Feigin-Stoyanovsky's type subspaces, was introduced by M. Primc who constructed bases of these subspaces in different cases ( [24][25][26]18]). These kind of subspaces were further studied by many authors ( [28,15,10,11,1,13,14,2,4,5,17,30], etc.) and the knowledge of presentation presents an important question in this study ([6-9, 27, 23]).…”