1. Complex Analysis;Ahlfors,1966
2. Lectures on the Hyperreals: An Introduction to Nonstandard Analysis;Goldblatt,1998
3. Subsystems of first and second order arithmetic;Horihata,2011
4. Nonstandard arithmetic and reverse mathematics;Keisler;Bull. Symbolic Logic,2006
5. Nonstandard arithmetic and recursive comprehension;Keisler;Ann. Pure Appl. Logic,2010