Perhaps you should try some spelling variations:
trinh dai » trinh tai, trinh di, trinh da
dang xay » dang van, van xay
va trinh » van trinh, va tinh, lap trinh
tu sach » thu sach, su sach, te sach
cuu tre » cau tren, cau treo
hieu ve » hieu va, hieu van
lang xa » lang ha, lang van
cua tre » cua te, cua triet, dua tren
am hoc » ad hoc
ve am » va am

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 y ((lang xa) OR (dang xay)) hoi. hieu ve am hoc va trinh dai ((cuu tre) or (cua tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach y ((lang xa) OR (dang xay)) hoi. hieu ve am hoc va trinh dai ((cuu tre) OR (cua tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach y ((lang xa) OR (dang xay)) hoi. hieu ve am hoc va trinh dai ((cuu tre) or (cua tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach y ((lang xa) OR (dang xay)) hoi. hieu ve am hoc va trinh dai ((cuu tre) or (cua tre))*.