Geometry & Topology Volume 6, issue 1 (2002)

1	J W Alexander, Note on Riemann spaces, Bull. Amer. Math. Soc. 26 (1920) 370 MR1560318
2	I Berstein, A L Edmonds, The degree and branch set of a branced covering, Invent. Math. 45 (1978) 213 MR0474261
3	R H Fox, Covering spaces with singularities, from: "A symposium in honor of S. Lefschetz", Princeton University Press (1957) 243 MR0123298
4	H M Hilden, Every closed orientable 3–manifold is a 3–fold branched covering space of $S^{3}$, Bull. Amer. Math. Soc. 80 (1974) 1243 MR0350719
5	H M Hilden, J M Montesinos, Lifting surgeries to branched covering spaces, Trans. Amer. Math. Soc. 259 (1980) 157 MR561830
6	U Hirsch, Über offene Abbildungen auf die 3–Sphäre, Math. Z. 140 (1974) 203 MR0362313
7	F Hosokawa, A Kawauchi, Proposals for unknotted surfaces in four-spaces, Osaka J. Math. 16 (1979) 233 MR527028
8	S Kamada, Nonorientable surfaces in 4–space, Osaka J. Math. 26 (1989) 367 MR1017592
9	, Problems in low-dimensional topology, from: "Geometric topology (Athens, GA, 1993)", AMS/IP Stud. Adv. Math. 2, Amer. Math. Soc. (1997) 35 MR1470751
10	W S Massey, Proof of a conjecture of Whitney, Pacific J. Math. 31 (1969) 143 MR0250331
11	J M Montesinos, A representation of closed orientable 3–manifolds as 3–fold branched coverings of $S^{3}$, Bull. Amer. Math. Soc. 80 (1974) 845 MR0358784
12	J M Montesinos, 4–manifolds, 3–fold covering spaces and ribbons, Trans. Amer. Math. Soc. 245 (1978) 453 MR511423
13	R Piergallini, Four-manifolds as 4–fold branched covers of $S^4$, Topology 34 (1995) 497 MR1341805
14	O Y Viro, The signature of a branched covering, Mat. Zametki 36 (1984) 549 MR771233