TITLE: Integration with values in a topological vector space
QUESTION [7 upvotes]: Is there a general theory of integration of functions with values in a topological vector space (not necessarily locally convex)?
Browsing through mathoverflow posts, I came across a discussion regarding Grothendieck's work on integration with values in a topological group L'intégration à valeurs dans un groupe topologique  (Reference request : Grothendieck's topological space valued integral ). Unfortunately the requested reference is never provided. Does anyone know of a rough sketch of the approach used?
Just to emphasize, I am interested in a general theory and not in notions such as the Bochner integral, or Gelfand-Pettis integral which use local convexity of the topological vector space.

REPLY [2 votes]: One reference ... 
Sion, Maurice, A theory of semigroup valued measures, Lecture Notes in Mathematics. 355. Berlin-Heidelberg-New York: Springer-Verlag. V, 140 p. DM 16.00; $ 6.60 (1973). ZBL0312.28016.