Global embeddings of scalar-tensor theories in (2+1)-dimensions
  We obtain (3+3)- or (3+2)-dimensional global flat embeddings of four uncharged and charged scalar-tensor theories with the parameters B or L in the (2+1)-dimensions, which are the non-trivially modified versions of the Banados-Teitelboim-Zanelli (BTZ) black holes. The limiting cases B=0 or L=0 exactly are reduced to the Global Embedding Minkowski Space (GEMS) solution of the BTZ black holes. 
Soon-Tae Hong, Won Tae Kim, Yong-Wan Kim, and Young-Jai Park