Perhaps you should try some spelling variations:
relational language » rational languages, national language, regional language
plain language » latin language, italian language
2f grammar » 22 grammar, 26 grammar, 27 grammar
2 grammar » 2 grammars, _ grammar, a grammar
2f early » 24 early, 21 early, 22 early
20 early » 10 early, 1720 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 (((20 early) OR (1820 early)))) works to 1800%22.
• The words AND, OR and NOT may confuse the search; try adding quotes: "%((plain language) or (relational language)) %((2f grammar) or (2 grammar)) %((2f early) or (((20 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 (((20 early) OR (1820 early)))) works to 1800%22*.