Please somebody comment my English.
It is hard to justify the external validity of the study since there was no reliability test and validity test of the measurement done in this study. Furthermore, the authors mentioned that “For the purpose of comparison, we randomly selected 1 issue of each of the study journals from 1999, randomly reduced the references to a maximum of 40 per research article, and then randomly selected a total of 40 references from each journal.” but without any explanation why they have chosen 40 as a maximum references per articles and then again randomly selected a total of 40 references from each journal.
no reliability test and validity test - I'd use 'or'
maximum references per articles- maximum number of references per article