Perhaps you should try some spelling variations:
dau truc » cau truc, dai truc, doan truc
vu khach » vu khanh, vu khac, vay khach
danh vai » danh sai, danh va, doanh van
hieu van » thien van, lieu va, hieu ve
su sach » so sach, vu sach
vai cua » dai cua, hai cua, lai cua
va danh » va dinh, va dan, va hanh
truc va » thuc va, thuc vat, trung va
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa

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) or (vu khach)) ky nang ma hoi. ((hieu van) OR (hieu va)) dau truc va danh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (vu khach)) ky nang ma hoi. ((hieu van) OR (hieu va)) dau truc va danh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (vu khach)) ky nang ma hoi. ((hieu van) OR (hieu va)) dau truc va danh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (vu khach)) ky nang ma hoi. ((hieu van) OR (hieu va)) dau truc va danh vai cua tre*.