Andrei Bulatov Martin E. Dyer Leslie Ann Goldberg Markus Jalsenius David Richerby The complexity of weighted Boolean #CSP with mixed signs. 3949-3961 2009 410 Theor. Comput. Sci. 38-40 http://dx.doi.org/10.1016/j.tcs.2009.06.003 db/journals/tcs/tcs410.html#BulatovDGJR09