@techreport{kam997,
 author = {D. Kr\'al', M. Krnc, M. Kupec, B. Lu{\v z}ar, and J. Volec},
 title = {Extending fractional precolorings},
 institution = {KAM-DIMATIA Series},
 year = {2011},
 number = {997},
 type = {prepublication}
}