In the study and erudition of oriental rugs, he will be best remembered for his books, "Oriental Rugs and the Stories They Tell", and "Armenian Rugs of the Gregorian Collection", done in collaboration with his daughter, Joyce Ballou Gregorian Hampshire and his grandson, Douglas Christian. In "Oriental Rugs and the Stories They Tell", he divided rugs into three major categories: tribal, village, and city rugs. He observed that it is often difficult for a novice to distinguish between a Sarouk, Isfahan or a Tabriz, but it is not difficult for the novice to distinguish between the innate characteristics of a village woven Bidjar and an intricate and highly stylized city woven Qum. "Oriental Rugs and the Stories They Tell" was a breakthrough in the study of rugs, because it made the study of rugs clear and accessible.