Need to write a literature review about Mobile-point-of-sale as a description LR since it's not applied yet in Saudi Arabia.
This research is based on implementing the (MPOS) in Saudi Arabia. NFS(digital wallets) and POS which are type of mobile payment, are common used everywhere in saudi, while Mpos not yet.
For the resources, make sure that they are Reliable sources from conferences or publications not a regular sites ( such as direct science or scholar etc )