[AH] Albrecht U., Hill P.: 
Butler groups of infinite rank and axiom 3. Czechoslovak Math. Jour. 37 (1987), 293-309. 
MR 0882600 | 
Zbl 0628.20045[B] Baer R.: 
Abelian groups without elements of finite order. Duke Math. Jour. 3 (1937), 68-122. 
MR 1545974 | 
Zbl 0016.20303[DR] Dugas M., Rangaswamy K.M.: 
Separable pure subgroups of completely decomposable torsion-free groups. Arch. Math. (Basel) (1992), 332-337. 
MR 1152619[H1] Hill P.: On the classification of abelian groups. photocopied manuscript, 1967.
[H2] Hill P.: 
Isotype subgroups of totally projective groups. Lecture Notes in Math. 874 Springer-Verlag New York (1973), 305-321. 
MR 0645937[HM1] Hill P., Megibben C.: 
On the theory and classification of abelian p-groups. Math. Zeit. 190 (1985), 17-38. 
MR 0793345 | 
Zbl 0535.20031[HM3] Hill P., Megibben C.: 
Pure subgroups of torsion-free groups. Trans. Amer. Math. Soc. 303 (1987), 765-778. 
MR 0902797 | 
Zbl 0627.20028[HM4] Hill P., Megibben C.: 
Knice subgroups of mixed groups. Abelian Group Theory Gordon-Breach New York (1987), 765-778. 
MR 1011306 | 
Zbl 0653.20057[HR] Hunter R., Richman F.: 
Global Warfield groups. Trans. Amer. Math. Soc. 266 (1981), 555-572. 
MR 0617551 | 
Zbl 0471.20038[Wal] Wallace K.: 
On mixed groups of torsion-free rank one with totally projective primary components. Jour. Algebra 17 (1971), 482-488. 
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Zbl 0215.39902[War] Warfield R.: 
A classification theorem for abelian p-groups. Trans. Amer. Math. Soc. 210 (1975), 149-168. 
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