  After different variables and functions changes, the generalized dispersal
problem, recalled in (1) below and considered in part I, see Labbas, Maingot
and Thorel [14], leads us to consider, to study and to invert the sum of linear
operators (4) below in a suitable Banach space by using two strategies: namely
the theory of sums of operators in Banach spaces as developed by Da
Prato-Grisvard [4] and successfully improved by Dore-Venni [5].
