Anderson, Robert J. & Ritter, William K. An Investigation of the Effect of Blade Curvature on Centrifugal-Impeller Performance, report, May 1, 1947; (https://digital.library.unt.edu/ark:/67531/metadc55452/m1/1/: accessed October 20, 2018), University of North Texas Libraries, Digital Library, digital.library.unt.edu; .