Abu Bashar I had once worked on a similar type of a research. At that time, I classified the literature review into three parts. The first part was a contextual review, where I included details about types of products, the markets where they are sold, the tastes and preferences of customers in that market etc. In the second part, I had included the review of a conceptual theory that can be linked to the topic. Here, you are researching on impulsive buying behavior. Many modern researchers feel that there cannot be anything called impulsive buying behavior (what appears impulsive to others, may be most thoughtful to the buyer). If that is to be hold as true, I suggest you to link your topic to Maslow's theory of motivation. You can classify buyers at various stages suggested by Maslow and study their requirements and psychology behind that. Lastly, you can get some research papers reviewed. It is also not a bad idea to include the interviews of some people working in industries where so called 'impulsive buying' is a common phenomena.
Purchases made during shopping trip to a store may be either planned or unplanned. Unplanned buying, alias impulse buying is a frequent experience which take place inside an organized retail format rather than in a traditional outlet. Here the customer’s behaviour is not being influenced by the traditional factors. He is persuaded by impulsiveness, which is a core aspect of human behaviour, and impulsiveness is ignited by different extrinsic elements which lead to actual purchase. A proper understanding of these factors could help the retail store promoters to craft out tactics which ultimately leads to purchase outside the shopping list. In a highly competitive retail segment, differentiated efforts could ensure impulse buying and thereby sustained growth of the store.