Perhaps you should try some spelling variations:
nang dau » hang dau, xang dau, nang du
hanh hai » thanh hai, nhanh hai, hang hai
su sach » so sach, vu sach
cac lop » cac hop, cac loai
cua tre » cuu tre, cua triet, dua tren
va hanh » van hanh, va thanh, va danh
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
hieu ve » hieu van
dau hai » dai hai, dau ha, cau hai
lop va » lap va, hop va, nop va
cua te » cua tu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang dau hai. ((hieu ve) or (hieu va)) cac lop va hanh hai ((cua tre) or (cua te))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang dau hai. ((hieu ve) OR (hieu va)) cac lop va hanh hai ((cua tre) OR (cua te)).
• Adding a wildcard symbol may retrieve word variants: su sach ky nang dau hai. ((hieu ve) or (hieu va)) cac lop va hanh hai ((cua tre) or (cua te))*.