Gramacy RB, Taddy MA. Categorical Inputs, Sensitivity Analysis, Optimization and Importance Tempering with tgp Version 2, an R Package for Treed Gaussian Process Models. J. Stat. Soft. [Internet]. 2010 Feb. 17 [cited 2024 Apr. 20];33(6):1-48. Available from: https://www.jstatsoft.org/index.php/jss/article/view/v033i06