2004. CALIBRATION OF THE PLIENSBACHIAN-TOARCIAN CALCAREOUS NANNOFOSSIL ZONE BOUNDARIES BASED ON AMMONITES (BASQUE-CANTABRIAN AREA, SPAIN). RIVISTA ITALIANA DI PALEONTOLOGIA E STRATIGRAFIA . 110, 1 (Mar. 2004). DOI:https://doi.org/10.13130/2039-4942/6271.