- A digraph is the union of two letters to represent one sound. - "Slips of Speech", John H. Bechtel.
- Should be, " A digraph is a union," etc. - "Slips of Speech", John H. Bechtel.
- 235. " An Improper Diphthong, or Digraph, is a diphthong in which only one of the vowels are sounded." - "The Grammar of English Grammars", Goold Brown.