Hi naveen,
Are familiar with GTS source, if yes check with your team mates. if your not sorry from my side.
What is GTS source, is it inbuilt on SAP ECC?
While implementing GTS extraction, your source team may know all where is extract sts and data source was there in gts source system.
Name the gts data sources? if its ecc inbulit, At RSA6 you can check the data sources and thru that you can find extract str.
its may not be easy to find as yout not familiar with bw. but try to get and play with them.
we are unable to show direclty.
Thanks