Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, tu cach
va lang » va nang, hoa lang
va hang » van hang, va nang, va hanh
cao thi » cau thi, cao tai, dao thi
hieu va » lieu va, hieu qua
su viet » so viet
nang xa » nang x, lang xa, nang ma
tu nang » tru nang, tu nong, tu nano
te sach » toc sach
tai su » tai so, tai tu, lai su
va cao » va cac, va co, 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 (te sach)) tu nang xa hoi. hieu va cao thi ((va hang) or (va lang)) tai su viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (te sach)) tu nang xa hoi. hieu va cao thi ((va hang) OR (va lang)) tai su viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (te sach)) tu nang xa hoi. hieu va cao thi ((va hang) or (va lang)) tai su viet".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) OR (te sach)) tu nang xa hoi. hieu va cao thi ((va hang) or (va lang)) tai su viet*.