Qualitative properties of trajectories of control systems: A survey P. H. ClarkeYu. S. LedyaevP. R. Wolenski OriginalPaper Pages: 1 - 48
Topological obstructions to the representability of functions by quadratures A. G. Khovanskii OriginalPaper Pages: 91 - 123
Flows on closed surfaces and behavior of trajectories lifted to the universal covering plane D. V. Anosov OriginalPaper Pages: 125 - 138