Lu, Y. (1997). Theoretical and experimental studies of a long stroke pumping unit with an auto-mechanical reverse mechanism and a sliding counterweight. Oulun yliopisto.
Lua i Stíl Chicago (17ú heag.)Lu, Yi. Theoretical and Experimental Studies of a Long Stroke Pumping Unit with an Auto-mechanical Reverse Mechanism and a Sliding Counterweight. Oulu: Oulun yliopisto, 1997.
Lua MLA (8ú heag.)Lu, Yi. Theoretical and Experimental Studies of a Long Stroke Pumping Unit with an Auto-mechanical Reverse Mechanism and a Sliding Counterweight. Oulun yliopisto, 1997.
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