@article{NSJOM_2000_30_2a_16,
     author = {R. 

 Doroslova\v{c}ki and O. Markovi\'c},
     title = {ri-Words over any alphabet without subword a b... b a for fixed a, b and k, 

 p},
     journal = {Novi Sad Journal of Mathematics},
     pages = {165-170},
     publisher = {mathdoc},
     volume = {30},
     number = {2},
     year = {2000},
     url = {http://geodesic.mathdoc.fr/item/NSJOM_2000_30_2a_16/}
}