@article{GDZPPN002332795,
title = {Geometry of normed bilinear maps and the 16-square problem.},
journal = {Mathematische Annalen},
volume = {283},
year = {1989},
pages = {437-448},
zbl = {0649.10015},
url = {http://dml.mathdoc.fr/item/GDZPPN002332795}
}
Lam, K.Y.; Yiu, P.Y.H. Geometry of normed bilinear maps and the 16-square problem.. Mathematische Annalen, Tome 283 (1989) pp. 437-448. http://gdmltest.u-ga.fr/item/GDZPPN002332795/