To cite the service as such, we suggest the following BibTeX entry:
@MISC{vo:ivoid_val, year=2015, title={Validator for {IVOA} Identifiers}, author={Markus Demleitner}, url={http://dc.zah.uni-heidelberg.de/ivoidval/q/val/info}, howpublished={{VO} resource provided by the {GAVO} Data Center} }