This primary source comes from the Records of the Patent and Trademark Office.
Full Citation: Shamrock Brew Label; 10/24/1933; 42849 - Shamrock Brew - J. J. Murphy Brewing Co.; Case Files for Registered Product Labels; Records of the Patent and Trademark Office, Record Group 241; National Archives at College Park. [Online Version, https://www.docsteach.org/documents/document/shamrock-brew-label, May 11, 2024]