1. Frege structures and the notions of proposition, truth and set;Aczel,1980
2. A modular hierarchy of logical frameworks;Adams,2004
3. A definitional approach to primitive recursion over higher order abstract syntax;Ambler,2003
4. Using typed λ-calculus to implement formal systems on a machine;Avron;J. Automat. Reason.,1992
5. Mechanized metatheory for the masses: the PoplMark challenge;Aydemir,2005