Perhaps you should try some spelling variations:
viec sach » viet sach, vien bach, dien sach
sach duoc » sach nuoc, sach dao, sach dung
hieu viec » nhieu viec, hieu ve, sieu viet
nhan tai » hang tai, van tai, toan tai
cua tre » cua te, cua triet, dua tren
va nhan » van nhan, ca nhan, va phan
duoc va » nuoc va, duc va, duoc ma
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
sang ma » tang ma, sang tao, mang may
nang ma » tang ma, nang cao, mang may
cuu 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: su sach ky ((nang ma) or (sang ma)) hoi. hieu viec sach duoc va nhan tai ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang ma) OR (sang ma)) hoi. hieu viec sach duoc va nhan tai ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang ma) or (sang ma)) hoi. hieu viec sach duoc va nhan tai ((cua tre) or (cuu tre))*.