erc: who: Koenig, D. R. what: Surface Ionization of Cesium and Thermionic Emission From Planar Single Crystals of Tungsten when: 19660601 where: https://digital.library.unt.edu/ark:/67531/metadc1027878/ erc-support: who: University of North Texas Libraries what: Permanent: Stable Content: when: 20081203 where: https://digital.library.unt.edu/ark:/67531/