David B. Massey Rodica Simion Richard P. Stanley Dirk L. Vertigan Dominic J. A. Welsh Günter M. Ziegler Lê Numbers of Arrangements and Matroid Identities. 118-133 1997 70 J. Comb. Theory, Ser. B 1 http://dx.doi.org/10.1006/jctb.1997.1755 db/journals/jct/jctb70.html#MasseySSVWZ97