Reference citations are needed for any statement in your proposal which is not of common knowledge and that requires information on the source. Focus on the few most relevant and most recent references, preferably those of international research journals. Avoid “grey” literature, text books and online or web references.
Some rules when citing references in the proposal text document:
A summary of green manure effects on soil parameters is presented by Becker (1987)
Green manure effects on soil parameters have been summarized previously (Becker, 1987)
A extensive review of Holocene palaeoenvironmental research in the central Sahara is given by Schütt and Krause (2009).
A review of Holocene palaeoenvironmental research in the central Sahara already exists (Schütt and Krause, 2009).
The geomorphology of the Nam Co Basin is examined by Schütt et al. (2007)
An geomorphological analysis of the Nam Co Basin already exists (Schütt et al., 2007).