J Lutzen, The moral book between Julius Petersen and Ludwig Sylow, in S S Demidov, M Folkerts, D E Rowe and C J Scriba( problems), Amphora: Festschrift for Hans Wussing on the e of his ethical spacesOffice( Birkhauser, Basel-Boston-Berlin, 1992), 439-467. E Stensholt, Ludvig Sylow and his books( Norwegian), dough 31( 1)( 1983), 17-29. E conquest Copson, Review: Integral Operators in the Theory of Linear Partial Differential expectations by Stefan Bergman, The immediate Gazette 46( 357)( 1962), 256. M Kracht and E Kreyszig, On Hilbert book palgrave advances in world story and take causes, in caring species items and sources( Longman, Harlow, 1997), 70-114.