@article{10_37236_1448,
     author = {Harald A. Helfgott and Ira M. Gessel},
     title = {Tilings of {Diamonds} and {Hexagons} with {Defects}},
     journal = {The electronic journal of combinatorics},
     year = {1999},
     volume = {6},
     doi = {10.37236/1448},
     url = {http://geodesic.mathdoc.fr/articles/10.37236/1448/}
}