jgg     2015 35 (5):  887-889    ISSN: 0412-1961  CN: 21-1139/TG Comparative Analysis on Scale Calibration for Invar Levelling Staff First Crust Monitoring and Application Center, CEA , 7 Naihuo Road, Tianjin 300180, China Received: 2015-03-05  Revised: null  Online: 2015-10-10 Supporting info