Douglas A. Cenzer, Jeffrey B. Remmel. Index Sets for Pi:::0:::::1:: Classes. Annals of Pure and Applied Logic, 93(1-3):3-61, 1998.
@article{CenzerR98b, title = {Index Sets for Pi:::0:::::1:: Classes}, author = {Douglas A. Cenzer and Jeffrey B. Remmel}, year = {1998}, researchr = {https://researchr.org/publication/CenzerR98b}, cites = {0}, citedby = {0}, journal = {Annals of Pure and Applied Logic}, volume = {93}, number = {1-3}, pages = {3-61}, }