https://en.wikipedia.org/wiki/Purgatory
https://www.quora.com/Why-do-orthodox-Christians-stand-while-praying
https://www.huffpost.com/entry/what-makes-orthodox-easter-different_b_9826838
https://www.christiancentury.org/article/critical-essay/why-orthodox-christians-see-triumph-cross
https://en.wikipedia.org/wiki/Fasting_and_abstinence_in_the_Catholic_Church
https://en.wikipedia.org/wiki/Great_Lent
https://www.lanternclub.com.au/blog/why-catholic-and-orthodox-easter-dates-are-different-every-year/
https://www.bbc.co.uk/newsround/48067272
https://www.quora.com/Which-denomination-is-more-conservative-Orthodox-Christianity-or-Catholicism
https://stpaulsirvine.org/can-a-homosexual-become-orthodox/
https://www.pewforum.org/2017/11/08/orthodox-take-socially-conservative-views-on-gender-issues-homosexuality/
https://www.orthodox.net/articles/about-crossing-oneself.html
https://www.bbc.co.uk/religion/religions/christianity/beliefs/trinity_1.shtml
https://www.dw.com/en/what-is-the-orthodox-church/a-45973747#:~:text=The%20Catholic%20Church%20believes%20the,and%20thus%20subject%20to%20error.&text=Most%20Orthodox%20Churches%20have%20both,so%20celibacy%20is%20an%20option.
https://en.wikipedia.org/wiki/First_seven_ecumenical_councils
https://en.wikipedia.org/wiki/East%E2%80%93West_Schism
https://en.wikipedia.org/wiki/James,_brother_of_Jesus
https://en.wikipedia.org/wiki/List_of_Christian_denominations_by_number_of_members
https://www.christianitytoday.com/biblestudies/bible-answers/theology/why-are-there-different-denominations.html
https://www.livescience.com/christianity-denominations.html
https://www.quora.com/Who-was-the-first-pope-Peter-or-James-the-Just