@article{10_4064_sm153_3_5,
     author = {M. Courbage and B. Kami\'nski},
     title = {On the directional entropy of ${\Bbb Z}^2$-actions
 generated by cellular automata},
     journal = {Studia Mathematica},
     pages = {285--295},
     publisher = {mathdoc},
     volume = {153},
     number = {3},
     year = {2002},
     doi = {10.4064/sm153-3-5},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/sm153-3-5/}
}