Perhaps you should try some spelling variations:
upon conversations » union conversations, open conversations, spoken conversations
christian upon » christians upon, christian union, christianity upon
reef history » reeves history, reef fishery
20th century » 18th century
2.1 germany » 21 germany, 2017 germany, 9.13 germany
2f 20th » 20 20th, 2.2 20th

You may be able to get more results by adjusting your search query.

• If you are trying to use Boolean operators, they must be ALL CAPS: %christian upon conversations %2.1 germany %((imf history) OR (((brief history) OR (reef history)))) %2f 20th century%22.
• Adding a wildcard symbol may retrieve word variants: %christian upon conversations %2.1 germany %((imf history) or (((brief history) or (reef history)))) %2f 20th century%22*.