S. Barry Cooper, C. S. Copestake. 2 Enumeration Degrees. Math. Log. Q., 34(6):491-522, 1988. [doi]
@article{CooperC88,
title = {2 Enumeration Degrees},
author = {S. Barry Cooper and C. S. Copestake},
year = {1988},
doi = {10.1002/malq.19880340603},
url = {http://dx.doi.org/10.1002/malq.19880340603},
researchr = {https://researchr.org/publication/CooperC88},
cites = {0},
citedby = {0},
journal = {Math. Log. Q.},
volume = {34},
number = {6},
pages = {491-522},
}