1. Beckwith R (2014) Pumping oil: 155 years of artificial lift. SPE J 66:101–107
2. Broren SG (2005) Rod saver speed control method and apparatus. Patent US20050095140A1
3. Brown KE (1980) The technology of artificial methods. Petroleum Publishing Company, Tulsa
4. Chi P, Yuan WX, Zhao ZP, Liu GB (2011) Energy-saving study and application of dual horsehead pump units. Inn Mong Petol Ind 21:17–18
5. Feng ZM, Ding HH, Jiang MZ (2015) New secondary balancing method saves energy for crank-balanced rod-pumping application. SPE Prod Oper 30:141–145