1. On the Structure of the Recursively Enumerable Degrees;Ambos-Spies,1980
2. Contiguous r.e. degrees;Ambos-Spies,1984
3. An extension of the nondiamond theorem in classical and α-recursion theory;Ambos-Spies;Journal of Symbolic Logic,1984
4. On pairs of recursively enumerable degrees;Ambos-Spies;Trans. Amer. Math. Soc.,1984
5. Antimitotic recursively enumerable sets;Ambos-Spies;Z. Math. Logik Grund. Math.,1985