Model for drag forces in the crevice of piston gauges in the viscous-flow and molecular-flow regimes Schmidt, J. W. ; Tison, S. A. ; Ehrlich, C. D. Abstract Publication: Metrologia Pub Date: 1999 DOI: 10.1088/0026-1394/36/6/16 Bibcode: 1999Metro..36..565S