Using two separate applications of "Lavud" in the same wall: Eruvin 9a; Succah 16b
"Lavud," applied vertically, is termed "Chavot": Eruvin 9a
This rule as a Law Spoken to Moshe at Sinai: Shabbat 97a; Eruvin 4b; Succah 6b
The difference between using "Lavud" at the bottom of a wall [Gediyyim Bokin Bah], for a gap which runs the height of a wall, and for a gap at the top of a wall: Eruvin 14b, 16b [2x]; Succah 16b
Considering raised areas which are beside a wall to be like part of the wall, itself: Eruvin 25a
Considering raised areas to be like the ground around them: Eruvin 100a