Hackworth, J. R., & Hackworth, F. D. (2004). Programmable logic controllers: Programming methods and applications. Merrill, Pearson Education.
Lua i Stíl Chicago (17ú heag.)Hackworth, John R., agus Frederick D. Hackworth. Programmable Logic Controllers: Programming Methods and Applications. Upper Saddle River, N.J. : New Delhi,IN.: Merrill, Pearson Education, 2004.
Lua MLA (8ú heag.)Hackworth, John R., agus Frederick D. Hackworth. Programmable Logic Controllers: Programming Methods and Applications. Merrill, Pearson Education, 2004.
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