Most of you are probably already pretty familiar with the SAP CRM data model. But nevertheless here are 2 useful files that will help you find back the relevant links between sap crm tables.
1- Data model - XLS file - Contribution by Gert-Jan Stolmeijer
2 - Data model view (PNG File) created by Nicolas Busson >>he also posted some useful blogposts on his site
Save the file locally and you can enlarge it by zooming in