@unpublished{Ammann-nd,
  author     = {Ammann, Andreas},
  title      = {Expressions of necessity: Catalan, its diachrony, and a problem for grammaticalization theory},
  type       = {manuscript},
  iso_code   = {cat},
  olac_field = {syntax; general_linguistics; typology},
  wals_code  = {ctl}
}