Ladefoged & Maddieson 1990

Peter Ladefoged and Ian Maddieson. 1990. Vowels of the world’s languages. Journal of Phonetics. 18. 93–122.

@article{
  author    = {Peter Ladefoged and Ian Maddieson},
  journal   = {Journal of Phonetics},
  number    = {2},
  pages     = {93–122},
  title     = {Vowels of the world’s languages},
  volume    = {18},
  year      = {1990}
}