The change history implemented in Sourcing is in some cases less than informative depending on the change. There are some changes such as lifecycle changes(phase change) that not only provide the who and when but the what as well. However if one needed to provide more indepth history onformation we have seen soe customers implement a more complete change history but utilizing extension collections and scripting. Please beware that this is also not an optimum situation as the amount of data collected on long lasting documents or master data can eventually have some performance impact.
When you say quotation, are you reffering to an attachment or just some data within the document?
Regards,
Gary