To cite the service as such, we suggest the following BibTeX entry:
@MISC{vo:gavo_crossmatch, year=2009, title={{GAVO} DC Custom Uploading Crossmatcher}, author={{GAVO} Data Centre}, url={https://dc.zah.uni-heidelberg.de/cross/q/match/info}, howpublished={{VO} resource provided by the {GAVO} Data Center} }