[1] R. Dimitrić: 
On pure submodules of free modules and $\kappa$-free modules. Abelian groups and modules (CISM, Udine, 1984). Courses and lectures - No. 287, pp. 373 - 381, Springer, Wien-New York, 1984. 
MR 0789833 
[2] R. Dimitrić: 
Chains of free modules and construction of $\kappa$-free modules. To appear in Rend. Sem. Mat. Univ. Padova, 1987. 
MR 0904618 
[3] R. Dimitrić, L. Fuchs: 
On torsion-free modules over valuation domains. To appear in Publ. Math. Debrecen, 1987. 
MR 0901009 
[5] L. Fuchs: 
On projective dimensions of modules over valuation domains. Abelian group theory (Honolulu, 1983). Lecture Notes in Math. 1006 (1983), 589-598. 
MR 0722651 | 
Zbl 0515.13012 
[6] L. Fuchs, L. Sake: 
Modules over valuation domains. Marcel Dekker, Inc., New York and Basel, 1985. 
MR 0786121