Share 'BI-CRM Extraction'

Hi Friends, Can someone send me a document which explains clearly how to extract CRM data into BI. I have gone through different links in SDN, but still could not get a clear picture of how its done. As I have been getting a lot of CRM requirements, I am trying to learn about this as I did not had a chance to work in this area till now. I would really appreciate if someone has those documents.…