Perhaps you should try some spelling variations:
cac nuoc » hoc nuoc, dat nuoc, cua nuoc
cap nuoc » dat nuoc
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
hieu va » hieu qua
va lang » va nang, hoa lang
lang vi » hang vi, lang va, sang vi
cua tre » cua te, cuu tre, cua triet
sach v » sach va, sach y, sach 2
v nang » va nang, vu nang, van nang
vi cua » vai 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 v nang xa hoi. ((hieu va) or (lieu va)) ((cac nuoc) OR (cap nuoc)) va lang vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach v nang xa hoi. ((hieu va) OR (lieu va)) ((cac nuoc) OR (cap nuoc)) va lang vi cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach v nang xa hoi. ((hieu va) or (lieu va)) ((cac nuoc) OR (cap nuoc)) va lang vi cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach v nang xa hoi. ((hieu va) or (lieu va)) ((cac nuoc) OR (cap nuoc)) va lang vi cua tre*.