Here are some places where you can look for information about HAMMER: Deformable Registration:

Homepage
HAMMER: Deformable Registration has a homepage that can be found at https://www.med.unc.edu/bric/ideagroup/free-softwares/fast-hammer
Forums
  1. open-discussion: General Discussion
  2. help: Get Public Help
Trackers
  1. Bugs: Bug Tracking System
  2. Support: Tech Support Tracking System
  3. Patches: Patch Tracking System
  4. Feature Requests: Feature Request Tracking System