Joseph E. Bonin Anna de Mier Marc Noy Lattice path matroids: enumerative aspects and Tutte polynomials. 63-94 2003 104 J. Comb. Theory, Ser. A 1 http://dx.doi.org/10.1016/S0097-3165(03)00122-5 db/journals/jct/jcta104.html#BoninMN03