Perhaps you should try some spelling variations:
tu sach » thu sach, te sach, tu cach
thi cuc » tai cuc
dau thi » cau thi, dan thi, dao thi
van hac » van hoc, van ha, van hai
van cac » van cau, van bac, dan cac
su sach » so sach, vu sach
lang xa » lang ha, dang xay, lang van
cuc tre » duc tre, cua tre, cuu tre
y lang » o lang, _ lang, tay lang
luc va » duc va, tuc va, loc va
va dau » va dao

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) or (su sach)) y lang xa hoi. hieu ((van cac) OR (van hac)) luc va dau thi cuc tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) y lang xa hoi. hieu ((van cac) OR (van hac)) luc va dau thi cuc tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) y lang xa hoi. hieu ((van cac) OR (van hac)) luc va dau thi cuc tre".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) y lang xa hoi. hieu ((van cac) OR (van hac)) luc va dau thi cuc tre*.