When developing with R6RS it is very useful to work with documents that incorporate the errata. I have rebuilt the specification from the repository above.
|R6RS Standard Libraries||PDF HTML|
|R6RS Non-Normative Appendices||PDF HTML|
|R6RS Rationale||PDF HTML|
Other Scheme specifications are also available online. John Cowan maintains the source of the R7RS and he has chased down and collected all the other Scheme specifications (except the IEEE edition and the JFP edition). R5RS errata are maintained by Richard Kelsey.