Perhaps you should try some spelling variations:
toc cach » hoc cach, toc sach, truoc cach
tru nang » tra nang, tri nang, truc nano
doi cua » dai cua, hoi cua
doi cuu » doi cuoc
va nang » van nang, da nang, cam nang
cam thu » nam thu, cac thu, ca thu
hieu va » lieu va, hieu qua
tu nano » truc nano
thu va » thuc va, thue va, tu va
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc cach ((tru nang) or (tu nano)) xa hoi. hieu va cam thu va nang ((doi cuu) OR (doi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc cach ((tru nang) OR (tu nano)) xa hoi. hieu va cam thu va nang ((doi cuu) OR (doi cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc cach ((tru nang) or (tu nano)) xa hoi. hieu va cam thu va nang ((doi cuu) OR (doi cua)) tre".
• Adding a wildcard symbol may retrieve word variants: toc cach ((tru nang) or (tu nano)) xa hoi. hieu va cam thu va nang ((doi cuu) OR (doi cua)) tre*.