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  1.  39
    Some Special Pairs of Σ2 e-Degrees.Seema Ahmad & Alistair H. Lachlan - 1998 - Mathematical Logic Quarterly 44 (4):431-449.
    It is shown that there are incomparable Σ2 e-degrees a, b such that every e-degree strictly less than a is also less than b.
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  2.  60
    Embedding the diamond in the σ2 enumeration degree.Seema Ahmad - 1991 - Journal of Symbolic Logic 56 (1):195 - 212.