In this paper, we give sufficient conditions on nonunitary operators on the Bergman space that imply the unitary operators.
JENA, PABITRA KUMAR
"Sufficient conditions on nonunitary operators that imply the unitary operators,"
Turkish Journal of Mathematics: Vol. 41:
2, Article 13.
Available at: https://journals.tubitak.gov.tr/math/vol41/iss2/13