@article{10_4064_aa_33_3_209_229,
     author = {Henryk Iwaniec},
     title = {On indefinite quadratic forms in four variables},
     journal = {Acta Arithmetica},
     pages = {209--229},
     publisher = {mathdoc},
     volume = {33},
     number = {3},
     year = {1977},
     doi = {10.4064/aa-33-3-209-229},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/aa-33-3-209-229/}
}