The remaining oral sounds are generally grouped together as 'consonants'. In them the stream of breath is interfered with in some way, so that a lesser resonance results, and a sharper, more incisive quality of tone.
- Sapir (1921), a pag.50

There are four main types of articulation generally recognized within the consonantal group of sounds.
- Sapir (1921), a pag.50

The oral manner of articulation is naturally not sufficient to define a consonant. The place of articulation must also be considerd.
- Sapir (1921), a pag.51