From QERM Wiki
Has anyone found better overview information on classes in R?
- S3 vs. S4 classes: R News Volume 4/1, June 2004 p. 33
- Class inheritance: Developments in Class Inheritance and Method Selection esp. combining S3 and S4
- S4 classes: Classes and Methods in the S Language
- Short overview: The R Inferno (among other things)
- J. M. Chambers. Software for Data Analysis: Programming with R. Springer, New York, 2008. ISBN 978-0-387-75935-7.