Cochrane Handbook for Systematic Reviews of Interventions - Look at Part One, Chapter Two for setting up protocols for systematic reviews.
Standards for Systematic Reviews - National Academies of Sciences, Engineering, and Medicine
JBI Reviewer's Manual - Joanna Briggs Institute
Systematic Review Data Repository (SRDR) from the Agency of Healthcare and Research Quality (AHRQ) - Accessing the extraction forms and tool require the user to sign up as a project contributor.
Distiller SR (Has a student pricing program) $
$ = These tools are not free.