1. S. Allen, D. Pask and A. Sims, A dual graph construction for higher-rank graphs, and K-theory for finite 2-graphs, Proceedings of the American Mathematical Society 134 (2006), 455–464.
2. T. Bates, D. Pask, I. Raeburn and W. Szymański, The C*-algebras of row-finite graphs, New York Journal of Mathematics 6 (2000), 307–324.
3. J. Cuntz and W. Krieger, A class of C*-algebras and topological Markov chains, Inventiones Mathematicae 56 (1980), 251–268.
4. M. Enomoto and Y. Watatani, A graph theory for C*-algebras, Mathematica Japonica 25 (1980), 435–442.
5. C. Farthing, Removing sources from higher-rank graphs, Journal of Operator Theory 60 (2008), 165–198.