@article {ClMa2005,
    author = {Claesson, Anders and Mansour, Toufik},
     title = {Enumerating permutations avoiding a pair of
              {B}abson-{S}teingr\'{\i}msson patterns},
   journal = {Ars Combin.},
  fjournal = {Ars Combinatoria},
    volume = {77},
      year = {2005},
     pages = {17--31},
      issn = {0381-7032},
}