It's important to clearly explain the criteria for including and excluding studies In the methodology section of a systematic review. It's also recommended to report the full search strategy in an appendix. The study selection should be documented using a PRISMA flow diagram.
Preferred Reported Items for Systematic Reviews and Meta-Analyses (PRISMA), is an international guideline for how a systematic review should be reported.
PRISMA Statement - Guidelines for Reporting Systematic Reviews
PRISMA flow diagram summarizes the process of searching for and evaluating literature, detailing the stages of identification, screening, eligibility, giving a clear overview of the number of studies included and excluded at each stage.