CELTA (/seltə/), (Certificate of English Language Teaching to Adults) is a pre-service training course and qualification  is a TEFL Qualification awarded by the University of Cambridge Local Examinations Syndicate (UCLES).
The CELTA Course Trainee Book by Scott Thornbury is availalbe to supplement the course; note there is also The CELTA Course Trainers Manual by Scott Thornbury and Peter Watkins, which is intended for teacher trainers who lead this course, though judging from the huh? reviews on Amazon it has been bought by some trainees.
CELTA is one of the best courses available, as it is nearly universally recognised by employers and governments. The other course that matches these criteria is CertTESOL.