Can't help with the DGJ reference, but it came from Jean Puraye's original 1966 article was published by the Musee d Armes de Liege and reproduced in The American Rifleman, April & May, 1976
http://parkerguns.org/history/Article.pdf has the 'Prince Albert' barrel

The Parker "Terell" barrel; Two Iron Crolle with 'TERELL' within the scrolls



The Pieper barrel



The "Remington Arms" two Iron Crolle. c. 1898 likely Presentation Grade 1894. Courtesy of Timothy Sheldon.