A. Leitsch, S. Hetzl, D. Weller, B. Woltzenlogel-Paleo:
"A Clausal Approach to Proof Analysis in Second-Order Logic";
in: "Lecture Notes in Computer Science, 5407", E. Artemov, A. Nerode (ed.); Springer LNCS, Heidelberg, 2009, ISBN: 3-540-92686-0, 214 - 229.
http://www.springerlink.com/content/5571058417433805/?p=e8a19411ffbb4535806494baf2525e62&pi=14