After two decades a second anchor for the VPDBδ13C scale Coplen, Tyler B. ; Brand, Willi A. ; Gehre, Matthias ; Gröning, Manfred ; Meijer, Harro A. J. ; Toman, Blaza ; Verkouteren, R. Michael Abstract Publication: Rapid Communications in Mass Spectrometry Pub Date: November 2006 DOI: 10.1002/rcm.2727 Bibcode: 2006RCMS...20.3165C