Whether we require a "doorway" joining the third wall to another wall, if that third wall is of minimal length: Succah 7a
Suspending the walls from the roof [using the Lavud principle of joining gaps within 3 Hand-Breadths of the ground]: Shabbat 97a; Eruvin 86b; Succah 16a-b
The allowable size of a gap in the wall: Succah 14b
Using the "Lavud" principle to join gaps in one, or multiple, walls: Succah 7a
Using the "Gud Asik" principle to pretend that walls reach the ceiling, where there are [not] recognizable walls: Succah 4b, 16a, 17a-18a
Stabbing four markers into a roof/ground where walls should begin, and making a roof overhead: Succah 4b
Using "Pi Tikrah Yored" to create an illusory wall at the end of a roof: Eruvin 25a-b, 93a, 95a; Succah 18b-19a
The above, for an alleyway which continues, uninterrupted, beyond the Succah: Succah 18b-19a
Considering the inclined wall of a tent, to be a wall of a Succah: Succah 19b
Entering a Succah which uses a tree as a wall, on a day when one may not move a tree: Eruvin 15a; Shabbat 154b
Using an alleyway where the entrance has a vertical beam, on Shabbat [because this is considered a "private" area for issues of Shabbat]: Succah 7a-b
Using the minimal walls constructed to allow use of a public well from the middle of the road on Shabbat, on Shabbat of Succot: Succah 7b
Which material is good for the walls: Succah 12a
Using a tree as a wall: Eruvin 15a; Succah 24b
Using a living animal for a wall: Eruvin 15b, 44a-b; Succah 23a-24b
Using a person as a wall: Eruvin 43b-44b
What happens if a wall falls down on Shabbat: Eruvin 44a