It was written when the pioneering work of Volterra and Fredholm was still fresh in the memory and while Hilbert, Erhard Schmidt and Weyl were in full flood.
Kapag ito ay nakasulat sa pangunguna ng trabaho ng Volterra at Fredholm ay sariwa pa rin sa memorya at habang Hilbert, Erhard Schmidt at Weyl ay sa buong baha.