Here you can find some Norton Guide mostly related to Clipper Programming:

CA Clipper 5.20
Guide To CA-Clipper
Error Messages
Technical Reference
Utilities
Release Notes
Sample Reference

CA Clipper 5.30
Guide To CA-Clipper
Error Messages
Technical Reference
Utilities

CA Cipper Tools
Book 1-3
Book 4-Appendices

Blinker 5
SIx Driver RDD v3.00
sxApi Reference Guide
Nanforum Toolkit v3.05
Class(y) v2.4
Clipper Internals
Internal Errors