no. 4
The ⊕ c -topology is not completable
Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 4, Tome 10 (1983) no. 4, pp. 579-586. 
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     title = {The $\oplus _c$-topology is not completable},
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     pages = {579--586},
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     zbl = {0537.20029},
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Mader, Adolf. The $\oplus _c$-topology is not completable. Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 4, Tome 10 (1983) no. 4, pp. 579-586. http://archive.numdam.org/item/ASNSP_1983_4_10_4_579_0/

[1] K. Benabdallah - J. Irwin, Pure N-high subgroups, p-adic topology and direct sums of cyclic groups, Canad. J. Math., 26 (1974), pp. 322-327. | MR | Zbl

[2] D. Boyer - A. Mader, Functorial topologies on abelian groups, Rocky Mountain J. Math., 10 (1980), pp. 695-708. | MR | Zbl

[3] B. Charles, Sous-groupes fonctoriels et topologies, Etudes Sur Les Groupes Abeliens, Dunod, Paris, 1968, pp. 75-92. | MR | Zbl

[4] D.O. Cutler - R.W. Stringall, A topology for primary abelian groups, Etudes Sur Les Groupes Abeliens, Dunod, Paris, 1968, pp. 93-100. | MR | Zbl

[5] G. D'Este, The ⊕c-topology on abelian groups, Ann. della Scuola Norm. Sup. Pisa Cl. Sci., 7 (1980), pp. 241-256. | Numdam | Zbl

[6] L. Fuchs, Infinite Abelian Groups, Voll. I, II, Academic Press, New York and London, 1970 and 1973. | MR | Zbl

[7] E. Howard, First and second category abelian groups with the n-adic topology, Pacific J. Math., 16 (1966), pp. 323-329. | MR | Zbl

[8] A. Mader, The p-adic hull of abelian groups, Transactions AMS, 187 (1974), pp. 217-229. | MR | Zbl

[9] A. Mader, Basic concepts of functorial topologies, Abelian Group Theory, Proceedings, Oberwolfach, 1981, Lecture Notes in Mathematics, 874, pp. 251-271, Springer-Verlag, Berlin - Heidelberg - New York, 1981. | MR | Zbl

[10] Ch. Megibben, Large subgroups and small homomorphisms, Michigan Math. J., 13 (1966), pp. 153-160. | MR | Zbl