Master's theses are scientific works. They are meant to show that you master the methodological tools, that you are able to adapt/further develop/apply them, and that you are aware of and able to build on the scientific state-of-the-art. This state-of-the-art is usually not found in textbooks but in recent papers published in scientific journals of the respective field. A useful link for performing literature research is http://scholar.google.at
A proxi for the scientific quality of a published paper is the journal in which it has been published. An orientation with respect to journal quality in the management field provides the VHB Journal Ranking (jourqual3): http://vhbonline.org/vhb4you/jourqual/vhb-jourqual-3/
When writing your thesis, cite papers using the american author-year citation style (APA). Make sure that you only list those works in your list of references to which you also refer in the text; and that all the required information is provided in the list of references (authors and/or editors, title, year, journal/publisher, pages, volume, doi, etc.) .