1. Models and Ultraproducts: An introduction;Bell,1969
2. Computability in p-radically closed fields and non-standard arithmetic;Dubrovsky,1971
3. Numbered fields;Ershov,1968
4. Orderings and Boolean algebras not isomorphic to recursive ones;Feiner,1967
5. Effective procedures in field theory;Froehlich;Trans. Roy. Philos. Soc. London Ser. A,1956