Perhaps you should try some spelling variations:
chat truc » cau truc, chat xuc
thu sach » tu sach, thuat sach, thuoc sach
sach ky » sac ky, sach y, sach ty
cao hoi » cau hoi, co hoi, cao hoc
hieu va » lieu va
truc va » thuc va, thuc vat, trung va
va danh » va dinh, va dan, va hanh
sai cua » hai cua, lai cua, bai cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: thu sach ky nang cao hoi. ((hieu va) OR (hieu qua)) chat truc va danh ((sai cua) or (dai cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu sach ky nang cao hoi. ((hieu va) OR (hieu qua)) chat truc va danh ((sai cua) OR (dai cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu sach ky nang cao hoi. ((hieu va) OR (hieu qua)) chat truc va danh ((sai cua) or (dai cua)) tre".
• Adding a wildcard symbol may retrieve word variants: thu sach ky nang cao hoi. ((hieu va) OR (hieu qua)) chat truc va danh ((sai cua) or (dai cua)) tre*.