Perhaps you should try some spelling variations:
dinh dieu » dinh dien, dinh tieu, vinh dieu
hieu cua » hieu qua, bieu cua, hieu ca
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
dieu cua » dieu tra
sach ky » sac ky, sach y, sach ty
nang xa » lang xa, nang ma, mang xa
va dinh » van dinh, va kinh, va tinh
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: tu ((sach ky) or (cac ky)) ((nang xa) OR (nang x)) hoi. hieu cua cac nuoc va dinh dieu cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (cac ky)) ((nang xa) OR (nang x)) hoi. hieu cua cac nuoc va dinh dieu cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (cac ky)) ((nang xa) OR (nang x)) hoi. hieu cua cac nuoc va dinh dieu cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (cac ky)) ((nang xa) OR (nang x)) hoi. hieu cua cac nuoc va dinh dieu cua tre*.