Schwarz and Green discovered T-duality, and constructed two superstring theories—IIA and IIB related by T-duality, and type I theories with open strings.
Schwarz a Green objavili T-dualitu a skonštruovali dve rôzne superstrunové teórie--- IIA a IIB korelované podľa T-duality, a teórie typu I s otvorenými strunami.