@inproceedings{pirkwieser-09,
 address = {Pisa, Italy},
 author = {Sandro Pirkwieser and Günther~R. Raidl},
 booktitle = {Proceedings of the International Network Optimization Conference 2009},
 editor = {Maria Grazia Scutell{\`a} and others},
 keywords = {hybrid, netdesign},
 title = {A Column Generation Approach for the Periodic Vehicle Routing Problem with Time Windows},
 url = {https://www.ac.tuwien.ac.at/files/pub/pirkwieser-09.pdf},
 year = {2009}
}