Perhaps you should try some spelling variations:
thanh hai » thanh phan, thanh hoa, thanh san
thuc day » thuc dan, thuc vat
hieu van » hieu va, thien van, lieu va
hai cuu » hai cua, hai chu, hai cuc
truc va » thuc va, thuc vat, trung va
van dau » van dao, phan dau
sang ky » sang kyo, tang ky, bang ky
lang xa » lang ha, dang xay, lang van
dang ky » dang y, dan ky, dong ky
cuu tre » cua tre, cau tren, cau treo

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu ((sang ky) OR (dang ky)) lang xa hoi. hieu van dau ((truc va) or (thuc day)) thanh hai cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sang ky) OR (dang ky)) lang xa hoi. hieu van dau ((truc va) OR (thuc day)) thanh hai cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sang ky) OR (dang ky)) lang xa hoi. hieu van dau ((truc va) or (thuc day)) thanh hai cuu tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sang ky) OR (dang ky)) lang xa hoi. hieu van dau ((truc va) or (thuc day)) thanh hai cuu tre*.