Book: Noel Hume, Ivor. 2001 If These Pots Could Talk: Collecting 200 Years of British Household Pottery.
• Discussion of "GR" Westerwald jugs and mugs: pp. 108-109, figs. V.20-V.23Catalogue: Hinton, Jack. 2012 The Art of German Stoneware from the Charles W. Nichols Collection and the Philadelphia Museum of Art.
• Westerwald jugs and mug with "GR" and varied ornamental motifs: p. 47, pl. 32, cobal and (one) manganese decoration.Book: Noel Hume, Ivor. 1969 Archaeology and Wetherburn's Tavern.
• Cylindrical "GR" mug excavated at Wetherburn's Tavern, Williamsburg, Virginia: p. 29, fig. 17Book: Shannon, Timothy J & Gellman, David N. 2014 American Odysseys: A History of Colonial North America. 400.