Beckmann, A., & Buss, S. R. (2014). Improved witnessing and local improvement principles for second-order bounded arithmetic. ACM Transactions on Computational Logic, 15(1), pp. 2:1-2:35. doi:10.1145/2559950

Beckmann, Arnold, and Samuel R. Buss. "Improved Witnessing and Local Improvement Principles for Second-order Bounded Arithmetic." ACM Transactions On Computational Logic 15, no. 1 (2014): 2:1-2:35.

Beckmann, Arnold, and Samuel R. Buss. "Improved Witnessing and Local Improvement Principles for Second-order Bounded Arithmetic." ACM Transactions On Computational Logic 15.1 (2014): 2:1-2:35.