@article{10_1017_S0017089500030536,
     author = {Lagrange, Jean},
     title = {Pythagorean ratios in arithmetic progression, part {II.} {Four} {Pythagorean} ratios},
     journal = {Glasgow mathematical journal},
     pages = {45--55},
     year = {1994},
     volume = {36},
     number = {1},
     doi = {10.1017/S0017089500030536},
     url = {http://geodesic.mathdoc.fr/articles/10.1017/S0017089500030536/}
}