Billy Joel | Joel Chandler Harris | Joel-Peter Witkin | Joel Schumacher | Joel Osteen | Joel Hodgson | Joel Whitburn | Joel Plaskett | Haley Joel Osment | Joel McHale | Joel McCrea | Joel Lamangan | Joel Grey | Joel | Mitch Joel | Joel Zifkin | Joel Spolsky | Joel Silver | Joel Salatin | Joel Hayward | Karl Amson Joel | Joel Wapnick | Joel Veitch | Joël Robuchon | Joel Porter | Joel Klein | Joel Futterman | Joel David Moore | Joel Daly | Joel Banal |
The classic 1976 work of Ferdinando Gliozzi, Joel Scherk and David Olive paved the way to a systematic understanding of the rules behind string spectra in cases where only closed strings are present via modular invariance but did not lead to similar progress for models with closed strings, despite the fact that the original discussion was based on the type I string theory.