#Need to condider
When I created ABAP Development Guidelines, I saw much information.
Following pages were very useful.
#Helpful Links
Development Guidelines for Greenfield Implementation in sync with SAP Custom Code Management
This page is custom code management rather than development guidelines.
"Best Practice Guidelines for Development - Practical tips" from DSAG
"Best Practice Guidelines for Development - Useful tips" from DSAG
DSAG always gives us very helpful information. The doc is brilliant.
SAP official guidelines
Its contents are not only ABAP but also BW, PI and other areas.
Github
The static check, which can be integrated with code inspector. Though I haven't import the checks, the contents were helpful.
#####ABAP Help
Needlsess to say, every ABAP engineer reads this help document. "ABAP - Programming Guidelines " was so helpful when creating our guidelines.