I am currently looking at various guidelines on how to write a research proposal and would be most grateful if smn could clarify a few concepts for me.

One guideline to write a research proposal requires that alongside 'the methodology to be followed', the key literature (and limitations) should be addressed; another guideline requires that in addition to research method, the 'sources to be consulted' are to be identified.

My question is what is the difference btwn 'key literature' and 'sources' ??? Are sources part and parcel of 'key literature' or should this perhaps be addressed within the frame of methodology?

Thank-you very much.