Perhaps you should try some spelling variations:
hanh thai » nhanh thai, hinh thai, hanh tai
thai cua » than cua, tai cuc, tri cua
duc manh » suc manh, duc anh, duc minh
quoc ban » quoc bao, quoc lan, quoc quan
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
hieu ve » hieu van
nang ho » nang hoc, nang co, tang ho
cua tre » cua te, cuu tre, cua triet
ho hai » hoc hai, pho hai, cho 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 ky nang ho hai. ((hieu ve) OR (hieu va)) cac ((quoc ban) or (duc manh)) hanh thai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ho hai. ((hieu ve) OR (hieu va)) cac ((quoc ban) OR (duc manh)) hanh thai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ho hai. ((hieu ve) OR (hieu va)) cac ((quoc ban) or (duc manh)) hanh thai cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ho hai. ((hieu ve) OR (hieu va)) cac ((quoc ban) or (duc manh)) hanh thai cua tre*.