Perhaps you should try some spelling variations:
hieu hieu » hien hieu, hieu hien, thien hieu
doanh van » doan van, doanh va, doanh ban
danh vai » danh sai, danh va, dang van
hieu cac » hieu luc, hieu va, hieu van
tu sach » thu sach, su sach, te sach
cua tre » cua te, cua triet, dua tren
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
ty nang » ky nang, ty xang, ty hang
cuu tre » cau tren, cau treo
cac ly » cac ky, cac le, cam ly
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: tu sach ty nang ma hoi. hieu hieu cac ly va ((danh vai) or (doanh van)) ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang ma hoi. hieu hieu cac ly va ((danh vai) OR (doanh van)) ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang ma hoi. hieu hieu cac ly va ((danh vai) or (doanh van)) ((cua tre) or (cuu tre))*.