Perhaps you should try some spelling variations:
dung doi » huong doi, dung tai, dung co
vat dung » van dung, va dung, viet dung
cac toc » cac toi, cac nuoc, cac thoi
doi cua » dai cua, hoi cua
cac tuc » cac tu, cac tac, cac nuoc
sach ty » sach tu, sach thu, xach tay
cua tu » cua tuc, cua su, cua cu
x hoi » xa hoi, o hoi, x ho

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) or (sach y)) nang x hoi. hieu qua ((cac tuc) OR (cac toc)) vat dung doi cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ty) OR (sach y)) nang x hoi. hieu qua ((cac tuc) OR (cac toc)) vat dung doi cua tu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach ty) or (sach y)) nang x hoi. hieu qua ((cac tuc) OR (cac toc)) vat dung doi cua tu".
• Adding a wildcard symbol may retrieve word variants: su ((sach ty) or (sach y)) nang x hoi. hieu qua ((cac tuc) OR (cac toc)) vat dung doi cua tu*.