W. & B. Douglas (Firm)

• W. & B. Douglas' descriptive catalogue and price list of patent pumps, hydraulic rams, chain pumps, garden engines, and other hydraulic machines, hardware, etc. manufactured at their works in Middletown, Connecticut, U.S.A. ... 1875-1876
• W. & B. Douglas' descriptive catalogue and price list of patent pumps, hydraulic rams, chain pumps, garden engines, and other hydraulic machines, hardware, etc., manufactured at their works, Middletown, Connecticut
• W. & B. Douglas' descriptive catalogue and price-list of patent pumps, hydraulic rams, yard hydrants, street washers, garden engines, pump chain, and other hydraulic machines, hardware, etc