Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
cac tac » cac toc, cac bac, cac dac
vat cua » bat cua, dat cua, hat cua
mat cua » ma cua, manh cua, mang cua
y nang » ky nang, ly nang, v nang
nang o » nang co, nang ho, nang ro
tac va » tac da, tac xa, tuc va
o hoi » co hoi, o hoc, o hai

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 y nang o hoi. hieu va cac tac va van ((vat cua) or (mat cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y nang o hoi. hieu va cac tac va van ((vat cua) OR (mat cua)) tre.
• Adding a wildcard symbol may retrieve word variants: tu sach y nang o hoi. hieu va cac tac va van ((vat cua) or (mat cua)) tre*.