Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
thanh di » thanh doi, thanh de, thanh do
va thanh » gia thanh, ban thanh, va tinh
cua tre » cua te, cuu tre, cua triet
cac hoc » cach hoc, cac hop, bac hoc
cac loc » cac lop, cac toc, cac nuoc
nang xa » nang x, lang xa, nang ma
san ky » sang ky, van ky, ban ky
dan ky » van ky
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((san ky) OR (dan ky)) nang xa hoi. hieu van ((cac loc) or (cac hoc)) va thanh di cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((san ky) OR (dan ky)) nang xa hoi. hieu van ((cac loc) OR (cac hoc)) va thanh di cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((san ky) OR (dan ky)) nang xa hoi. hieu van ((cac loc) or (cac hoc)) va thanh di cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((san ky) OR (dan ky)) nang xa hoi. hieu van ((cac loc) or (cac hoc)) va thanh di cua tre*.