Perhaps you should try some spelling variations:
dinh viet » ninh viet, danh viet, trinh viet
cam truc » nam truc, lam truoc, nam truoc
viet cua » viec cua, viet ca, viet qua
su sach » so sach, vu sach
va dinh » van dinh, va kinh, va tinh
cua tre » cua te, cuu tre, cua triet
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
ky lang » ky nang, ky dang, ky tang

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 (do sanh)) ky lang xa hoi. hieu va ((cam truc) OR (cau truc)) va dinh viet cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (do sanh)) ky lang xa hoi. hieu va ((cam truc) OR (cau truc)) va dinh viet cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) or (do sanh)) ky lang xa hoi. hieu va ((cam truc) OR (cau truc)) va dinh viet cua tre".
• Adding a wildcard symbol may retrieve word variants: ((su sach) or (do sanh)) ky lang xa hoi. hieu va ((cam truc) OR (cau truc)) va dinh viet cua tre*.