@article { M.Makhaniok1997,
	title = {Limit Cycles of a Planar Vector Field},
	journal = {Acta Appl. Math.},
	volume = {48},
	year = {1997},
	pages = {13-32},
	author = {Makhaniok , M. and Hesser , J. and M{\"a}nner , R. and Noethe , S.}
}
@conference { M.Makhaniok1992,
	title = {Attractors of Two-Dimensional Dynamical Systems},
	booktitle = {WOPPLOT 92},
	year = {1992},
	author = {Makhaniok , M. and Hesser , J. and Noethe , S. and Maenner , R.}
}
