  In an article from 2008, A. Akhmedov and B. D. Park constructed irreducible
symplectic 4-manifolds homeomorphic but not diffeomorphic to the manifolds
CP^2#3CP^2bar and 3CP^2#5CP^2bar. These manifolds are constructed by using
generalized fibre sums. In this note we describe an explicit splitting of the
second (co-)homology of these manifolds adapted to their construction as fibre
sums. We also calculate the canonical classes of the symplectic structures.
This gives a new proof for a formula derived by A. Akhmedov, R. I. Baykur and
B. D. Park.
