GoshkoL. V., and PortenkoN. I. 1994. “Limit Theorems for the Number of Crossings of a Fixed Plane by Certain Sequences of Generalized Dbffusion Processes”. Ukrains’kyi Matematychnyi Zhurnal 46 (4), 357–371. https://umj.imath.kiev.ua/index.php/umj/article/view/5732.