Perhaps you should try some spelling variations:
dinh viet » ninh viet, danh viet, trinh viet
viet cua » viec cua, viet ca, viet qua
su sach » vu sach
so sach » so sanh, bo sach, co sach
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
va dinh » van dinh, va kinh, va tinh
cua tre » cua te, cuu tre, cua triet
du va » dau va, tu va, su va

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 (so sach)) ky ((nang x) or (tang ma)) hoi. hieu va cac du va dinh viet cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) ky ((nang x) OR (tang ma)) hoi. hieu va cac du va dinh viet cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (so sach)) ky ((nang x) or (tang ma)) hoi. hieu va cac du va dinh viet cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (so sach)) ky ((nang x) or (tang ma)) hoi. hieu va cac du va dinh viet cua tre*.