TY  - RPRT
TI  - Complex geometry, quantum tunneling, and time machines.
AU  - LX Li
AU  - JM Xu
AU  - L Liu
PY  - 1993
DO  - 10.1103/physrevd.48.4735
UR  - https://pubmed.ncbi.nlm.nih.gov/10016128/
ID  - 10016128
ER  -