Season 2, Episode 15 "Revelations"
Season 2, Episode 16 "Fear and Loathing"
Season 2, Episode 17 "Distress"
Season 2, Episode 18 "Jones"
Season 2, Episode 19 "Ashes and Dust"*
Season 3, Episode 15 "A Higher Power"*
Season 3, Episode 16 "Elephant's Memory"
*only one line that refers to it.