Perhaps you should try some spelling variations:
cam truc » cau truc, nam truc, lam truoc
dau tren » dau tien, dat tren, dau tieng
tu sach » thu sach, su sach, te sach
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu van
hieu va » lieu va, hieu qua
truc va » thuc va, thuc vat, trung va
y nang » ky nang, ly nang, v nang
va dan » ca dan, va dao, va dau
ca dau » ca dao, ca dan, va dau

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 cao hoi. ((hieu ve) OR (hieu va)) cam truc va dan ca dau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y nang cao hoi. ((hieu ve) OR (hieu va)) cam truc va dan ca dau tren".
• Adding a wildcard symbol may retrieve word variants: tu sach y nang cao hoi. ((hieu ve) OR (hieu va)) cam truc va dan ca dau tren*.