Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
tru nang » tra nang, tri nang, truc nano
va danh » va dinh, va hanh, dia danh
vai cua » dai cua, hai cua, lai cua
cao suc » cao su, cao duc
nang xa » nang x, lang xa, nang ma
qua cao » qua cac, qua ca, qua cai
va dan » ca dan, va dao, va dau
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((toc sach) or (doc sach)) tru nang xa hoi. hieu qua cao suc ((va danh) OR (va dan)) vai cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) tru nang xa hoi. hieu qua cao suc ((va danh) OR (va dan)) vai cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (doc sach)) tru nang xa hoi. hieu qua cao suc ((va danh) OR (va dan)) vai cua te".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) tru nang xa hoi. hieu qua cao suc ((va danh) OR (va dan)) vai cua te*.