Classification framework in conceptual paper I would like to ask you for a piece of advice concerning the justification of the classification framework in a systematic review article.

I am writing an article in a retailing context and I want to classify from a marketing perspective. I managed to classify some of the articles. However, I do not know what approaches I can use for the classification.

I was thinking to categorize the articles into sub-disciplines such as consumer behaviour, innovations etc. but I am not sure if there is a way to justify the subjective criteria. 

Moreover, probably similar categorizations have been already used even it is in regards to other concepts, not those that I want to explore, so I am afraid if I can prove my contribution in my paper.

How should I proceed?
Read more of the articles. Or at least read more of the article abstracts, before you begin classification. If a similar classification has already been used, just re-use that--it's already been demonstrated once. For a systematic review, the classification methods are analogous to the 'methods'--replication is a virtue. The papers you review are the data. If you bring new data, apply a good method, you will make a useful contribution.