SAP SD full revision at one go: -
SAP SOD Certification link: -
How to register for SAP certification?
How to get S-Id?
SAP IDOCS basics
SAP SD interview questions: -
http://www.sap4india.in/SAP-SD-Sample-Certification-Questions-in-Sales-Order-Processing.html
List of IDoc Transactions: -
http://www.education.iama2z.com/tutorial/sap/idoc_transactions_code.html
List of IDoc Transactions: -
http://www.education.iama2z.com/tutorial/sap/idoc_transactions_code.html