Extra explanation and practice
For more explanation on the basics of articles (if needed):
https://www.myenglishpages.com/site_php_files/grammar-lesson-concessions.php
For more exercises (advanced and proficiency) on Reported speech (if needed):
https://www.myenglishpages.com/site_php_files/grammar-exercise-although.php
https://test-english.com/grammar-points/b2/clauses-contrast-purpose-reason-result/