@article{10_4153_CJM_1970_064_7,
     author = {Thomason, S. K.},
     title = {Sublattices and {Initial} {Segments} of the {Degrees} of {Unsolvability}},
     journal = {Canadian journal of mathematics},
     pages = {569--581},
     year = {1970},
     volume = {22},
     number = {3},
     doi = {10.4153/CJM-1970-064-7},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1970-064-7/}
}