@article{MS2_1979__45_166673,
     author = {W.J. Ryan},
     title = {Proof of the quadratic reciprocity law in primitive recursive arithmetic.},
     journal = {Mathematica Scandinavica},
     pages = {177--197},
     publisher = {mathdoc},
     volume = {45},
     year = {1979},
     zbl = {0433.03024},
     url = {http://geodesic.mathdoc.fr/item/MS2_1979__45_166673/}
}