Recently I have submitted an article to a journal. One of their comment was "The reference list should have link of each reference next to it". I am finding it challenging to address this comment properly.
Muhaiminul - the journal most likely means the 'online' link. For most new articles, this means the link to the unique Digital Object Identifier (DOI) number/URL. For older/journals not registered for DOI - then the 'next best' thing is the original website retrieval URL link.
Most probably they want DOI number or direct URL link to find the paper easily. You can add these links and DOI number with reference using EndNote easily.
Reference links are also local index as for ex. code universel ( УДК ) in russian journals. It is not difficult to using, but i it takes at least two generations to regularize the codes.