  The structure of Ge$_{22}$Ga$_3$Sb$_{10}$S$_{65}$ and
Ge$_{15}$Ga$_{10}$Sb$_{10}$S$_{65}$ glasses was investigated by neutron
diffraction (ND), X-ray diffraction (XRD), and extended X-ray absorption fine
structure (EXAFS) measurements at the Ge, Ga and Sb K-edges. Experimental data
sets were fitted simultaneously in the framework of the reverse Monte Carlo
(RMC) simulation technique. Short range order parameters were determined from
the obtained large-scale configurations. It was found that the coordination
numbers of Ge, Sb and S are around the values predicted by the Mott-rule (4, 3
and 2, respectively). The Ga atoms have on average 4 nearest neighbors. The
structure of these stoichiometric glasses can be described by the chemically
ordered network model: Ge-S, Ga-S and Sb-S bonds are the most important. Long
Sb-S distances (0.3 - 0.4 {\AA} higher than the usual covalent bond lengths)
are observed, suggesting that Sb atoms can be found in various local
environments.
