Path Integral by Space-time Slicing Approximation In Open Bosonic String   Field
  In our paper, we considered how to apply the traditional Feynman path integral to string field. By constructing the complete set in Fock space of non-relativistic and relativistic open bosonic string fields, we extended Feynman path integral to path integral on functional field and use it to quantize open bosonic string field. 
Am-Gil Ri, Tae-Song Kim, Chol-Man Ri and Song-Jin Im
physics.gen-ph