Perhaps you should try some spelling variations:
dinh thi » dinh tri
dang xay » dang van, van xay
tu sach » thu sach, su sach, te sach
thi cua » thai cua, thi cuc, tri cua
va dinh » van dinh, va kinh, va tinh
cac lop » cac hop, cac loai
sach ty » sach y, sach tu, sach thu
hieu va » hieu qua
lang xa » lang ha, lang van
lop va » lap va, hop va, nop va
cua tu » cua tuc, cua su, cua cu

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 ty ((lang xa) OR (dang xay)) hoi. ((hieu va) or (lieu va)) cac lop va dinh thi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((lang xa) OR (dang xay)) hoi. ((hieu va) OR (lieu va)) cac lop va dinh thi cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty ((lang xa) OR (dang xay)) hoi. ((hieu va) or (lieu va)) cac lop va dinh thi cua tu".
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((lang xa) OR (dang xay)) hoi. ((hieu va) or (lieu va)) cac lop va dinh thi cua tu*.