Perhaps you should try some spelling variations:
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
su sach » so sach, vu sach
hang vi » hang va, hanh vi, hang di
lang vi » lang va, sang vi, lang viet
hieu va » lieu va, hieu qua
vu nang » vuc nang, va nang, vu dang
cua tre » cua te, cuu tre, cua triet
v nang » va nang, van nang, voi nang

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 ((v nang) OR (vu nang)) xa hoi. hieu va cac nuoc va ((lang vi) or (hang vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((v nang) OR (vu nang)) xa hoi. hieu va cac nuoc va ((lang vi) OR (hang vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((v nang) OR (vu nang)) xa hoi. hieu va cac nuoc va ((lang vi) or (hang vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((v nang) OR (vu nang)) xa hoi. hieu va cac nuoc va ((lang vi) or (hang vi)) cua tre*.