Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
nam thuc » nam thuoc, am thuc, nam thu
hanh vai » hanh va, hanh tai, hanh van
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, su sach, te sach
sach ty » sach y, sach tu, sach thu
xang xa » lang xa, mang xa, ang xa
thuc xa » thuc xay, tuc xa, thuc va
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ty xang xa hoi. hieu van nam thuc xa ((hanh vai) OR (hanh vi)) ((cua tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty xang xa hoi. hieu van nam thuc xa ((hanh vai) OR (hanh vi)) ((cua tre) OR (cau tren))*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty xang xa hoi. hieu van nam thuc xa ((hanh vai) OR (hanh vi)) ((cua tre) or (cau tren))*".