The Burkill-Cesari B-C
integrals arising in L. Cesari’s theory of quasi additive vector-valued set functions
need not be additive as functions of sets. It is shown in the present paper that these
integrals satisfy quasi additivity and overadditivity properties. These properties are
used to prove Banach-type differentiation theorems for B-C integrals defined
on Euclidean spaces. Variants of Cesari’s basic quasi additivity hypothesis
and some simplifications in the formulation of the general theory are also
discussed.