This is a link of different SAP that can be used as a reference when digging out for knowledge, training or solutions.
SAP Service Marketplace
Catalogue to all SAP products and links to other official SAP sites.
SAP Help Portal
SAP Community Network (SCN)
Forum with thousand of questions and answers from SAP users and developers.
SAP Training & Certification Shop
SAP Official Training Courses and Certificates
Free courses of the most recent SAP products.