Mireille Bousquet-Mélou Marko Petkovsek Linear recurrences with constant coefficients: the multivariate case. 51-75 2000 225 Discrete Mathematics 1-3 http://dx.doi.org/10.1016/S0012-365X(00)00147-3 db/journals/dm/dm225.html#Bousquet-MelouP00