To cite the service as such, we suggest the following BibTeX entry:
@MISC{vo:GAVO_DC_full_PMH, year=2012, title={{GAVO} DC searchable registry {PMH} interface}, author={{GAVO} Data Centre}, url={http://dc.zah.uni-heidelberg.de/rr/q/pmh/info}, howpublished={{VO} resource provided by the {GAVO} Data Center} }