Perhaps you should try some spelling variations:
vu khach » vu khanh, vay khach, cua khach
hieu van » hieu va, thien van, lieu va
su sach » so sach, vu sach
vu khac » vu kham, vu khanh, bui khac
nang ma » tang ma, sang ma, nang cao
van cau » van dau, van hau, van chat
truc va » thuc va, thuc vat, trung va
dan hai » doan hai, dang hai, dan khai
hai cua » thai cua, dai cua, hoi cua
cua tre » cua te, cuu tre, cua triet
ma hoi » mai hoi, xa hoi, ma hoa
va dan » ca dan, va dao, va dau

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