F. Besau, F. Schuster:
"Binary operations in spherical convex geometry";
Indiana Univ.Math.J., 65 (2016), 4; 1263 - 1288.
http://dx.doi.org/10.1512/iumj.2016.65.5867Electronic version of the publication:
https://www.iumj.indiana.edu/IUMJ/FULLTEXT/2016/65/5867