Lattices in $\mathbb Z^2$ and the congruence $xy+uv \equiv c (mod m)$
Volume 132 / 2008
Acta Arithmetica 132 (2008), 127-133
MSC: 11A07, 11H06, 11H55, 11B75.
DOI: 10.4064/aa132-2-2
