Perhaps you should try some spelling variations:
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
dong cua » dung cua, cong cua, huong cua
su sach » so sach, vu sach
ly nang » ky nang, ly hang, ly quang
ly vang » ly hang, ly van, ly quang
hieu ve » hieu va, hieu van
va hanh » van hanh, va thanh, va danh
ve cac » va cac, vien cac
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 ((ly nang) OR (ly vang)) xa hoi. hieu ve cac nuoc va hanh ((di cua) or (dong cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((ly nang) OR (ly vang)) xa hoi. hieu ve cac nuoc va hanh ((di cua) OR (dong cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((ly nang) OR (ly vang)) xa hoi. hieu ve cac nuoc va hanh ((di cua) or (dong cua)) tre".
• Adding a wildcard symbol may retrieve word variants: su sach ((ly nang) OR (ly vang)) xa hoi. hieu ve cac nuoc va hanh ((di cua) or (dong cua)) tre*.