@article{AFM_1986_11_2_a2,
     author = {H. A. Maurer and A. Salomaa and E. Welzl and D. Wood},
     title = {Denseness, maximality, and decidability of grammatical families},
     journal = {Annales Fennici Mathematici},
     pages = {167--178},
     publisher = {mathdoc},
     volume = {11},
     number = {2},
     year = {1986},
     doi = {10.5186/aasfm.1986.1114},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.5186/aasfm.1986.1114/}
}