Perhaps you should try some spelling variations:
te sach » toc sach
thi cua » thai cua, thi cuc, tri cua
dan thi » dang thi, tran thi, dinh thi
cac tac » cac toc, cac bac, cac dac
hieu va » lieu va, hieu qua
cac tuc » cac toc, cac tu, cac nuoc
cua tre » cua te, cuu tre, cua triet
ha hoi » hoa hoi, ha noi, xa hoi
y lang » o lang, tay lang, yen lang
va dan » ca dan, va dao, va dau
_ lang » o lang, _ land

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

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