Text ( visual ) : unmediated Studies in service and self-control / by Hugh Hartshorne, Mark A. May and Julius B. Maller. -- New York : Macmillan , 1929. -- xvii, 559 p. ; 21 cm. -- (Studies in the nature of character / by Character Education Inquiry ; 2). -- Includes index ; Book 1: Studies in service, Book 2: Studies in self-control. -- (BA36389422) ; https://ci.nii.ac.jp/ncid/BA36389422 Author Heading(s): Hartshorne, Hugh ; May, Mark Arthur ; Maller, Julius B.