@article{PORMA_1972__31_3_115169,
     author = {Porter, A. Duane},
     title = {Systems of four equations with a matrix application in a finite field},
     journal = {Portugaliae mathematica},
     pages = {121--131},
     publisher = {mathdoc},
     volume = {31},
     number = {3},
     year = {1972},
     mrnumber = {0302618},
     zbl = {0243.15012},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/PORMA_1972__31_3_115169/}
}