Reference: Firchow and Firchow 1969

Firchow, Irwin & Jacqueline Firchow. 1969. An abbreviated phoneme inventory. Anthropological Linguistics 11(9). 271–276.

@article{firchow1969abbreviated,
  author  = {Firchow, Irwin and Firchow, Jacqueline},
  journal = {Anthropological Linguistics},
  number  = {9},
  pages   = {271–276},
  title   = {An abbreviated phoneme inventory},
  volume  = {11},
  year    = {1969}
}