Klaus Ambos-Spies. Sublattices of the Polynomial Time Degrees. Inf. Comput., 65(1):63-84, April 1985.
@article{Ambos-spies85:0, title = {Sublattices of the Polynomial Time Degrees}, author = {Klaus Ambos-Spies}, year = {1985}, month = {April}, researchr = {https://researchr.org/publication/Ambos-spies85%3A0}, cites = {0}, citedby = {0}, journal = {Inf. Comput.}, volume = {65}, number = {1}, pages = {63-84}, }