Perhaps you should try some spelling variations:
upon conversations » union conversations, open conversations, spoken conversations
christians upon » christians among, christians from, christians being
20th century » 18th century
ref history » reef history, brief history, bief history
21 germany » 11 germany, 2 germany, 20 germany
2021 20th » 2021 24th, 2020 20th, 2021 10th