Perhaps you should try some spelling variations:
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
su sach » so sach, vu sach
hieu va » lieu va, hieu qua
va hang » van hang, va nang, va lang
vai cua » dai cua, hai cua, lai cua
y nang » ky nang, ly nang, may nang
v nang » va nang, vu nang, van nang
vi cua » di cua

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