@article{10_37236_1675,
     author = {Alexander Burstein and Toufik Mansour},
     title = {Words restricted by patterns with at most 2 distinct letters},
     journal = {The electronic journal of combinatorics},
     year = {2002},
     volume = {9},
     number = {2},
     doi = {10.37236/1675},
     zbl = {1021.05002},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/1675/}
}