Reference

All functions
ssp.glm()	Optimal Subsampling Methods for Generalized Linear Models
ssp.quantreg()	Optimal Subsampling Methods for Quantile Regression Model
ssp.relogit()	Optimal Subsampling for Logistic Regression Model with Rare Events Data
ssp.softmax()	Optimal Subsampling Method for Softmax (multinomial logistic) Regression Model
subsampling-package subsampling	Optimal Subsampling Methods for Statistical Models