Heiko Vogler. The OI-Hierarchy Is Closed under Control. Inf. Comput., 78(3):187-204, September 1988.
@article{Vogler88:0, title = {The OI-Hierarchy Is Closed under Control}, author = {Heiko Vogler}, year = {1988}, month = {September}, researchr = {https://researchr.org/publication/Vogler88%3A0}, cites = {0}, citedby = {0}, journal = {Inf. Comput.}, volume = {78}, number = {3}, pages = {187-204}, }