Perhaps you should try some spelling variations:
lang van » dang van, tang van, hoang van
dang xay » dang van, van xay
hieu cua » hieu qua, dieu cua, bieu cua
su triet » su viet, su tien, ve triet
su sach » so sach, vu sach
sach ty » sach y, sach tu, sach thu
thuc va » thuc vat, thuc dan, thuc day
va doan » va doanh, van doan, va dan
cua am » cua tam, cua nam, cua dam

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 ty ((lang van) or (dang xay)) hoi. hieu cua am thuc va doan va su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((lang van) OR (dang xay)) hoi. hieu cua am thuc va doan va su triet.
• Adding a wildcard symbol may retrieve word variants: su sach ty ((lang van) or (dang xay)) hoi. hieu cua am thuc va doan va su triet*.