Physica C paper.
The excitation energy spectrum for a system with electron pairs tunneling in a two-leg ladder has a doping depended gap (also at arxiv.org).
In a search for a “simple” model of HTSC
P.S. You can find more at researchgate or academia.edu or http://arxiv.org/
P.P.S. I understand that for a mature physicist my papers might bring forth feelings, I experience sometimes when reading what a mature physicist writes about teaching :)
P.P.P.S. Statistics on March 10th 2015 => not bad for a guy who has no formal education in English