Perhaps you should try some spelling variations:
dinh thi » dinh tri
hieu va » lieu va, hieu qua
thi cua » thai cua, thi cuc, tri cua
va dinh » van dinh, va kinh, va tinh
nang xa » nang x, lang xa, mang xa
cac lop » cac hop, cac loai
nang ma » tang ma, sang ma, nang cao
sach ky » sac ky, sach ty, sach kem
lop va » lap va, hop va, nop va
cua te » cua tu

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: thu ((sach ky) or (sach y)) ((nang xa) OR (nang ma)) hoi. hieu va cac lop va dinh thi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: thu ((sach ky) OR (sach y)) ((nang xa) OR (nang ma)) hoi. hieu va cac lop va dinh thi cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "thu ((sach ky) or (sach y)) ((nang xa) OR (nang ma)) hoi. hieu va cac lop va dinh thi cua te".
• Adding a wildcard symbol may retrieve word variants: thu ((sach ky) or (sach y)) ((nang xa) OR (nang ma)) hoi. hieu va cac lop va dinh thi cua te*.