Perhaps you should try some spelling variations:
relational language » rational languages, national language, regional language
plain language » latin language
2f grammar » 22 grammar, 26 grammar, 27 grammar
2 grammar » 2 grammars, _ grammar, a grammar
2f early » 20 early, 21 early, ef early

Try widening your search to All Fields.

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: %((plain language) OR (relational language)) %((2f grammar) OR (2 grammar)) %((2f early) OR (1820 early)) works to 1800%22.
• Adding a wildcard symbol may retrieve word variants: %((plain language) or (relational language)) %((2f grammar) or (2 grammar)) %((2f early) or (1820 early)) works to 1800%22*.