Perhaps you should try some spelling variations:
nay lang » nam lang, nhan lang, va lang
tay lang » tai lang, tay tang, tay quang
hieu van » hieu va, thien van, lieu va
hac nuoc » hoc nuoc, cac nuoc, phap nuoc
tu sach » thu sach, su sach, te sach
van hac » van hoc, van ha, van hai
vi cua » vai cua, di cua
cua tu » cua tuc, cua su, cua cu

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((nay lang) OR (tay lang)) xa hoi. hieu van hac nuoc ((va tinh) or (may tinh)) vi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((nay lang) OR (tay lang)) xa hoi. hieu van hac nuoc ((va tinh) OR (may tinh)) vi cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((nay lang) OR (tay lang)) xa hoi. hieu van hac nuoc ((va tinh) or (may tinh)) vi cua tu".
• Adding a wildcard symbol may retrieve word variants: tu sach ((nay lang) OR (tay lang)) xa hoi. hieu van hac nuoc ((va tinh) or (may tinh)) vi cua tu*.