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4 Open and Closed Strings
The algebraic structure of open string theory with non-abelian gauge groups was
discussed in
• M. R. Gaberdiel and B. Zwiebach, “Tensor Constructions of Open String
Theories I: Foundations”, Nucl.Phys. B505 (1997) 569–624, and
• M. R. Gaberdiel and B. Zwiebach, “Tensor Constructions of Open String
Theories II: Vector bundles, D-branes and orientifold groups”, Phys.Lett. B410
(1997) 151–159.