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Annals of Mathematics 142(3), pages 527–595. Publisher page: annals.math.princeton.edu/1995/142-3/p04

DOI: doi.org/10.2307/2118554

The symplectic-sum construction glues along codimension-two symplectic submanifolds with identified opposite normal bundles. The publisher abstract verifies the resulting realization of finitely presented groups in every even dimension at least four. For the local gluing model and normal-bundle conditions, the Auroux–Smith lectures give a complementary primary exposition.