Barragán, S., M. Fernández, C. Rueda, and S. Peddada. “Isocir: An R Package for Constrained Inference Using Isotonic Regression for Circular Data, With an Application to Cell Biology”. Journal of Statistical Software, vol. 54, no. 4, Sept. 2013, pp. 1-17, doi:10.18637/jss.v054.i04.