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
20 germany » 2 germany, 7 germany, 8 germany
2.2 20th » 2020 20th, 2023 20th, 2021 20th