Transformations in 4 Dimensions
- 2012 Introducing HTDP 3.1 to transform coordinates across time and spatial reference frames by Chris Pearson and Richard Snay. GPS Solutions, doi:10.1007/s10291-012-0255-y.
- 2010 Coping with Tectonic Motion by Richard Snay and Chris Pearson. The American Surveyor Magazine, Vol. 7, No. 9.
- 2010 HTDP 3.0: Software for coping with the coordinate changes associated with crustal motion by Chris Pearson, Robert McCaffrey, Julie L. Elliott, and Richard Snay. Journal of Surveying Engineering, doi: 10.1061/(ASCE)SU.1943-5428.0000013.
- 2007 Updating HTDP for two recent earthquakes in California by Chris Pearson and Richard Snay. Surveying and Land Information Science, Vol. 67, No. 3, pp. 149-158.
- 2003 NGS Geodetic Toolkit, Part 5: Horizontal Time-Dependent Positioning by Richard Snay. Professional Surveyor Magazine, Vol. 23, No. 11.
- 1999 Using the HTDP software to transform spatial coordinates across time and between reference frames by Richard A. Snay. Surveying and Land Information Systems, Vol. 59, No. 1, pp. 15-25.