Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
hang vai » hang tai, hang hai, hang vi
cam duc » cam xuc, cao duc, pham duc
van cam » van nam, van lam, van cau
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
mai hoi » mai khoi, dai hoi, lai hoi
mau hoi » cau hoi, mau ho, mau hop
ky dang » ky nang, ky danh
cuu tre » cua tre, cau tren, cau treo

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ky dang ((mau hoi) OR (mai hoi)). hieu van cam duc va ((hang vai) or (hang va)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky dang ((mau hoi) OR (mai hoi)). hieu van cam duc va ((hang vai) OR (hang va)) cuu tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky dang ((mau hoi) OR (mai hoi)). hieu van cam duc va ((hang vai) or (hang va)) cuu tre*".