@article{MZ_1978__163_172738,
     author = {Sergio Invernizzi and Fabio Zanolin},
     title = {On the {Existence} and {Uniqueness} of {Periodic} {Solutions} of {Differential} {Delay} {Equations.}},
     journal = {Mathematische Zeitschrift},
     pages = {25--38},
     year = {1978},
     volume = {163},
     zbl = {0369.34035},
     url = {http://geodesic.mathdoc.fr/item/MZ_1978__163_172738/}
}