Bercovici Hari and Jung Il Bong and Ko Eungil and Pearcy Carl: Generalizations of the relation of quasisimilarity for operators. In: Acta scientiarum mathematicarum, (85) 3-4. pp. 681-691. (2019)
Cowen Carl C. and Ko Eungil and Thompson Derek A. and Tian Feng: Spectra of some weighted composition operators on H2. In: Acta scientiarum mathematicarum, (82) 1-2. pp. 221-234. (2016)