1. Homotopy of non-singular vector fields to structurally stable ones;Asimov;Ann. Math.,1975
2. Round handles and non-singular Morse–Smale flows;Asimov;Ann. Math.,1975
3. W. Jaco and P. Shalen: Mapping a Seifert fibered space into a 3-manifold (to appear).
4. Geschlossen flächen in dreidimensionalen mannigfaltigkeiten;Kneser;J. ber. dts. Mat-Verein,1929
5. A unique decomposition theorem for 3-manifolds;Milnor;Am. J. Math.,1964