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Warrington, A. R. van C. (1968-01-01). "Relay Design and Construction: Characteristics—Choice of Measuring Units—Construction of Measuring Units—Construction of Timing Units—Details of Design—Cases—Panel Mounting—Operation Indicators—Finishes". Protective Relays. Springer US. pp. 29–49. doi:10.1007/978-1-4684-6459-7_2. ISBN978-1-4684-6461-0.
Rockefeller, G.D.; Udren, E.A. (1972-05-01). "High-Speed Distance Relaying Using a Digital Computer II-Test Results". IEEE Transactions on Power Apparatus and Systems. PAS-91 (3): 1244–1258. Bibcode:1972ITPAS..91.1244R. doi:10.1109/TPAS.1972.293483. ISSN0018-9510.
Khan, Z.A; Imran, A. (2008-03-01). "Algorithms and hardware design of modern numeric overcurrent and distance relays". 2008 Second International Conference on Electrical Engineering. pp. 1–5. doi:10.1109/ICEE.2008.4553897. ISBN978-1-4244-2292-0. S2CID34642073.
Sham, M.V.; Vittal, K.P. (2011-12-01). "Development of DSP based high speed numerical distance relay and its evaluation using hardware in loop power system simulator". ISGT2011-India. pp. 37–42. doi:10.1109/ISET-India.2011.6145351. ISBN978-1-4673-0315-6. {{cite book}}: |journal= ignored (help)
Elneweihi, A.F.; Schweitzer, E.O.; Feltis, M.W. (1993). "Negative-sequence overcurrent element application and coordination in distribution protection". IEEE Transactions on Power Delivery. 8 (3): 915–924. doi:10.1109/61.252618. ISSN0885-8977.
Rockefeller, G.D.; Udren, E.A. (1972-05-01). "High-Speed Distance Relaying Using a Digital Computer II-Test Results". IEEE Transactions on Power Apparatus and Systems. PAS-91 (3): 1244–1258. Bibcode:1972ITPAS..91.1244R. doi:10.1109/TPAS.1972.293483. ISSN0018-9510.
Mooney, Joe (March 25–28, 1996). Microprocessor-Based Transmission Line Relay Applications. American Public Power Association's Engineering & Operations Workshop. Salt Lake City, Utah: Schweitzer Engineering Laboratories, Inc. p. 1.
Khan, Z.A; Imran, A. (2008-03-01). "Algorithms and hardware design of modern numeric overcurrent and distance relays". 2008 Second International Conference on Electrical Engineering. pp. 1–5. doi:10.1109/ICEE.2008.4553897. ISBN978-1-4244-2292-0. S2CID34642073.
Rockefeller, G.D.; Udren, E.A. (1972-05-01). "High-Speed Distance Relaying Using a Digital Computer II-Test Results". IEEE Transactions on Power Apparatus and Systems. PAS-91 (3): 1244–1258. Bibcode:1972ITPAS..91.1244R. doi:10.1109/TPAS.1972.293483. ISSN0018-9510.
Elneweihi, A.F.; Schweitzer, E.O.; Feltis, M.W. (1993). "Negative-sequence overcurrent element application and coordination in distribution protection". IEEE Transactions on Power Delivery. 8 (3): 915–924. doi:10.1109/61.252618. ISSN0885-8977.