In this document, "Cheresh" refers to a person who is Deaf and Mute. Please note that many of the laws relating to a "Cheresh" do not necessarily apply to all people who are deaf and mute; it depends on mental ability, as well.
Their ability to Learn: Chagigah 3a
"Daat" (Overall Mental Competence): Chagigah 2b; Yevamot 104b; Gittin 22b, 23a
Deaf, vs. Mute and Deaf: Chagigah 2b; Niddah 13b