Quaternion gravity

1. Three roads to quaternion gravity PDF 2018, 13 pages, technical paper
2. Measurement-101
   • Measuring events
   • Special relativity
   • Quaternion gravity
   • SR + GR: Special relativity and quaternion gravity
3. Quaternion space-times-time invariance as gravity
4. The 2015 Essays on Gravitation contest
5. The PGT - Personal Gravity Theory - Homework Assignment