[1] Corner A.L.S., Göbel R.: 
Prescribing endomorphism algebras – A unified treatment. Proc. London Math. Soc. (3) 50 (1985), 447–479. 
MR 0779399[2] Dugas M., Göbel R.: 
Endomorphism rings of separable torsion-free abelian groups. Houston J. Math. 11 (1985), 471–483. 
MR 0837986[3] Eklof P.C., Mekler A.H.: 
Almost Free Modules. revised ed., North-Holland, New York, 2002. 
MR 1914985[4] Fuchs L.: Infinite Abelian Groups – Vol. 1 & 2. Academic Press, New York, 1970, 1973.
[5] Göbel R., Herden D., Salazar Pedroza H.G.: 
$\aleph_k$-free separable groups with prescribed endomorphism ring. Fund. Math. 231 (2015), 39–55. 
DOI 10.4064/fm231-1-3 | 
MR 3361234[6] Göbel R., Herden D., Shelah S.: 
Prescribing endomorphism algebras of $\aleph_n$-free modules. J. Eur. Math. Soc. 16 (2014), no. 9, 1775–1816. 
DOI 10.4171/JEMS/475 | 
MR 3273308[8] Göbel R., Shelah S., Strüngmann L.: 
$\aleph_n$-free modules over complete discrete valuation domains with almost trivial dual. Glasgow J. Math. 55 (2013), 369–380. 
DOI 10.1017/S0017089512000614 | 
MR 3040868[9] Göbel R., Trlifaj J.: Approximations and Endomorphism Algebras of Modules – Vol. 1 & 2. Expositions in Mathematics, 41, Walter de Gruyter, Berlin, 2012.
[11] Herden D.: Constructing $\aleph_k$-free structures. Habilitationsschrift, University of Duisburg-Essen, 2013.
[14] Salazar Pedroza H.G.: Combinatorial principles and $\aleph_k$-free modules. PhD Thesis, University of Duisburg-Essen, 2012.
[15] Shelah S.: 
$\aleph_n$-free abelian groups with no non-zero homomorphisms to $\mathbb{Z}$. Cubo 9 (2007), 59–79. 
MR 2354353