Albert Atserias Maria Luisa Bonet Juan Luis Esteban Lower Bounds for the Weak Pigeonhole Principle and Random Formulas beyond Resolution. 136-152 2002 176 Inf. Comput. 2 http://dx.doi.org/10.1006/inco.2002.3114 db/journals/iandc/iandc176.html#AtseriasBE02