- ver.1: First draft
- ver.2: Second draft. The first circulation.
- ver.3: Appendices added. Minor modifications on Abstract
- ver.4: Minor update
- ver.5: Minor update
- ver.6: Updates reflecting comments
- ver.7: Updates based on further comments
- ver.8: Ready-to-submit version. Updates based on further comments
- ver.9: Defense presentation attached
- ver.10: Defense presentation updated
- ver.11: Modified version reflecting comments from referees
- ver.12: Whole directory of the latex files added