Primary research consists of a collection of original primary data. It is often undertaken after the researcher has gained some insight into the issue by reviewing secondary research or by analyzing previously collected primary data. It can be accomplished through various methods including questionnaires and telephone interviews in market research or experiments and direct observations in the physical sciences, amongst others. The term primary research is widely used in academic research, market research and competitive intelligence. There are advantages and disadvantages to primary research. Secondary research involves the summary, collation of existing research rather than primary research, where data is collected from  for example, research subjects or experiments. The term is widely used in medical research, legal research and in market research. The principal methodology in medical secondary research is the systematic review, commonly using meta-analytic statistical techniques, although other methods of synthesis, like realist reviews and meta-narrative reviews have been developed in recent years. Such secondary research uses the primary research of others typically in the form of research publications and reports.

Thank you for your answer. We are also looking for scholarly- or research-based sources to cite in our literature review with some definitions such as these valuable ones you have proposed. Do you know of any sources we might reference or have you written on this topic? Thank you for your help.

If after Kiran's answer you still have questions, I suppose you're taking the word 'literature' in a specific sense. Please, define clearly what is the dictionary entry that defines the word 'literature' the way you're using.

I mean research and scholarly literature, rather than fiction.