ГОСТ:
Toby B. H., Von Dreele R. B. GSAS-II: the genesis of a modern open-source all purpose crystallography software package //Journal of Applied Crystallography. — 2013. — T.46. —№. 2 —C. 544-549
MLA:
Toby, Brian H., and B. R. Von Dreele. "GSAS-II: the genesis of a modern open-source all purpose crystallography software package" Journal of Applied Crystallography 46.2 (2013): 544-549