The 5 Criteria for Evaluation
of Right Concentration:

After emerging from the deepest state so far attained one reviews it thus:
1: This absorption is Happy now, and
results in future happiness too...
2: This absorption is Noble, and unrivaled by anything in this world...
3: This absorption is not reached by inferior, or unworthy persons...
4: This absorption is entered upon & emerged from
while fully aware...
5: This absorption is perfectly Calm, Stilled, Unified, and neither
fabricated, nor suppressible, nor reversible, nor deniable...

Meditation
Manuals here:
https://What-Buddha-Said.net/library/pdfs/anapanasati.pdf
https://What-Buddha-Said.net/library/pdfs/Main_Meditation_Manual.pdf
Source: The Exhaustive Speeches by the
Buddha. Digha Nikāya 34
http://www.pariyatti.com/book.cgi?prod_id=25103
https://What-Buddha-Said.net/library/ati_website/html/tipitaka/dn/index.html
