Karel Hrbacek. Degrees of analytic Sets. Math. Log. Q., 29(2):75-82, 1983. [doi]
@article{Hrbacek83, title = {Degrees of analytic Sets}, author = {Karel Hrbacek}, year = {1983}, doi = {10.1002/malq.19830290204}, url = {http://dx.doi.org/10.1002/malq.19830290204}, researchr = {https://researchr.org/publication/Hrbacek83}, cites = {0}, citedby = {0}, journal = {Math. Log. Q.}, volume = {29}, number = {2}, pages = {75-82}, }