Perhaps you should try some spelling variations:
thanh tai » thanh hai, thanh toan, doanh tai
hanh tai » hang tai, han tai, hinh tai
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
cau tuc » cau truc, cau tu, cau luc
van cau » van dau, van hau, van chat
sach ky » sac ky, sach y, sach ty
mang xa » lang xa, mang may, dang xay
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 ky ((mang xa) or (nang x)) hoi. hieu van cau tuc xa ((hanh tai) OR (thanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((mang xa) OR (nang x)) hoi. hieu van cau tuc xa ((hanh tai) OR (thanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky ((mang xa) or (nang x)) hoi. hieu van cau tuc xa ((hanh tai) OR (thanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((mang xa) or (nang x)) hoi. hieu van cau tuc xa ((hanh tai) OR (thanh tai)) cua tre*.