Back in the 90's there was a popular magazine called GuptaPRO, later renamed CenturaPRO, published by Dian Schaffhauser and Mark Hunter. Many talented writers wrote articles for this magazine and shared their knowledge with the community.
Unfortunately the magazine closed down in 2000. ITG has collected the CenturaPRO issues to publish them here as a courtesy to the Gupta/Centura developers community.
The source code to all articles can be downloaded here as a single zip archive (15.3 MB). The monthly issues can be downloaded in pdf format separately.