Perhaps you should try some spelling variations:
sach vuc » sach duoc, sach nuoc, sach truc
vuc nang » cuc nang, vu nang, chuc nang
hieu van » thien van, lieu va, hieu ve
than duc » tran duc, phan duc, than doc
su sach » so sach, vu sach
cao hoi » cau hoi, co hoi, cao hoc
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
doi cua » dai cua, hoi cua
di cua » dai cua, de cua, do 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 vuc nang cao hoi. ((hieu van) or (hieu va)) than duc va hanh ((di cua) OR (doi cua)) tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach vuc nang cao hoi. ((hieu van) OR (hieu va)) than duc va hanh ((di cua) OR (doi cua)) tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach vuc nang cao hoi. ((hieu van) or (hieu va)) than duc va hanh ((di cua) OR (doi cua)) tre".
• Adding a wildcard symbol may retrieve word variants: su sach vuc nang cao hoi. ((hieu van) or (hieu va)) than duc va hanh ((di cua) OR (doi cua)) tre*.