Perhaps you should try some spelling variations:
sach nuoc » sach duoc, bach tuoc, dich nuoc
hieu vien » hieu hien, thieu nien, hieu tieng
hieu viec » nhieu viec, hieu ve, sieu viet
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
hanh di » hanh vi, hanh de, hang di
va hanh » van hanh, va thanh, va danh
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
cua tre » cua te, cuu tre, cua triet
di cua » dai cua, doi cua, de 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 ky nang xa hoi. ((hieu vien) or (hieu viec)) ((sach nuoc) OR (cac nuoc)) va hanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang xa hoi. ((hieu vien) OR (hieu viec)) ((sach nuoc) OR (cac nuoc)) va hanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang xa hoi. ((hieu vien) or (hieu viec)) ((sach nuoc) OR (cac nuoc)) va hanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang xa hoi. ((hieu vien) or (hieu viec)) ((sach nuoc) OR (cac nuoc)) va hanh di cua tre*.