@article{10_4153_CJM_1967_051_2,
     author = {Appel, K. I. and Parker, E. T.},
     title = {On {Unsolvable} {Groups} of {Degree} p = 4q + 1, p and q {Primes}},
     journal = {Canadian journal of mathematics},
     pages = {583--589},
     year = {1967},
     volume = {19},
     number = {1},
     doi = {10.4153/CJM-1967-051-2},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1967-051-2/}
}