Online Books and Articles
Hearing Shofar: The Still Small Voice of the Ram’s Horn by Michael Chusid: This three-volume compendium of “all things shofar” is a free download. It is accompanied by a robust blog with further insights.
The Shofar, by Cyrus Adler: This classic essay was published by The Smithsonian Institution in 1894.
Exotic Shofars by Rabbi Natan Slifkin: A guide to shofarot made from animal horns besides sheep or goats.
Videos
Shofar Practice Guide by Arthur Finkle: This series of four videos discusses the period leading up to Rosh Hashanah and the steps a shofar sounder is to take to practice and prepare.
Websites
Other Publications
The Shofar Sounder, Arthur Finkle (1993), Torah Aura Publications
Easy Guide to Shofar Sounding, Arthur Finkle (2002), Torah Aura Publications
Responsa, Repairing a Shofar, Arthur Finkle (2000), Hebrew Union College Library
Teka BeShofar: A Shofar Blowing Manual, Avrohom Reit, Feldheim