Perhaps you should try some spelling variations:
bach tuoc » sach duoc, sach nuoc
hieu viec » nhieu viec, hieu ve, sieu viet
viec bach » vien bach, viec ban, viec bao
nhan tai » hang tai, van tai, toan tai
tai cua » thai cua, tai cuc, tri cua
va nhan » van nhan, ca nhan, va phan
tuoc va » thuoc va, nuoc va, duoc va
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
sang ma » tang ma, sang tao, sang tai
nang ma » tang ma, nang cao
cua tre » cua te, cuu tre, cua triet

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 (mang may))) or (sang ma)) hoi. hieu viec bach tuoc va nhan tai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((((nang ma) OR (mang may))) OR (sang ma)) hoi. hieu viec bach tuoc va nhan tai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((((nang ma) OR (mang may))) or (sang ma)) hoi. hieu viec bach tuoc va nhan tai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((((nang ma) OR (mang may))) or (sang ma)) hoi. hieu viec bach tuoc va nhan tai cua tre*.