Please note that in this document, "Shofar" refers to the Ram's Horn.
Source for using an animal horn, specifically: Rosh HaShanah 33b
Which animals' horns are used: Rosh HaShanah 26a
The difference between the "Shofar" and the "Chatzotzrah": Succah 34a [See Rashi]
Doing the Mitzvah with a beautiful Shofar: Shabbat 133b
The horn must be held in the way in which it grows: Rosh HaShanah 27b, 34a
Preparation of associated necessities on Shabbat: Shabbat 131a-b
The Shofar is used as a symbol of the offering of Isaac: Rosh HaShanah 16a
The Shofar brings the merits before Hashem for Judgment: Shabbat 131b
Coating the Shofar with gold, in/out of the mouthpiece: Rosh HaShanah 27a, 27b [2x]
A Shofar lined internally with gold: Rosh HaShanah 27b [2x]
A Shofar which was cracked or broken, and re-sealed: Rosh HaShanah 27a
Lengthwise vs. Widthwise cracks: Rosh HaShanah 27b
A Shofar with a sealed hole in it: Rosh HaShanah 27b [3x]
A Shofar which was abbreviated or thinned: Rosh HaShanah 27b
A Shofar within a Shofar: Rosh HaShanah 27b
An Inside-Out Shofar: Rosh HaShanah 27b
If material was added to the Shofar: Rosh HaShanah 27b
If the soft material inside wasn't entirely hollowed out: Rosh HaShanah 27b
A horn from a Burnt Offering or Celebratory Offering while it was still alive: Rosh HaShanah 28a
A horn from a Condemned City of Idolatry: Rosh HaShanah 28a
A horn from Idolatry: Rosh HaShanah 28a
A horn from which someone had Vowed not to receive Benefit: Rosh HaShanah 28a
Cleaning the Shofar in a respectful fashion: Rosh HaShanah 33a
The Shofar is an item of a Mitzvah, not an item of intrisic holiness, and so it may be disposed of after the Mitzvah is over: Megillah 26b