A1:
https://learnenglishteens.britishcouncil.org/study-break/reading-zone/a1-graded-reading
A2:
https://learnenglishteens.britishcouncil.org/study-break/reading-zone/a2-graded-reading
B1:
https://learnenglishteens.britishcouncil.org/study-break/reading-zone/b1-graded-reading