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

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

• 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) OR (va hanh)) vai ((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) OR (va hanh)) vai ((cua tre) or (cau tren))~".
• Adding a wildcard symbol may retrieve word variants: tu sach ty xang xa hoi. hieu van nam thuc ((xa hanh) OR (va hanh)) vai ((cua tre) or (cau tren))*.