@article{700090,
     title = {The geometric theory of Volterra integral equations - a preliminary report},
     booktitle = {Proceedings of Equadiff III},
     series = {GDML\_Books},
     publisher = {Univ. J. E. Purkyn\v e - P\v r\'\i rodov\v edeck\'a fakulta},
     address = {Brno},
     year = {1973},
     pages = {139-143},
     mrnumber = {MR0346445},
     zbl = {0319.45003},
     url = {http://dml.mathdoc.fr/item/700090}
}

Sell, George R. The geometric theory of Volterra integral equations - a preliminary report, dans Proceedings of Equadiff III, GDML_Books,  (1973), pp. 139-143. http://gdmltest.u-ga.fr/item/700090/