Perhaps you should try some spelling variations:
cau tren » cu tren, dau tren, ca tren
hieu van » hieu va, thien van, lieu va
van hanh » van thanh, ban hanh, van anh
cuu tre » cua tre, cau treo
hanh di » hanh vi, hanh de, hang di
luc van » luoc van, luu van, duc van
sach ty » sach y, sach tu, sach thu
tu sach » thu sach, su sach, te sach
lang xa » lang ha, dang xay, lang van
nang xa » nang x, nang ma, mang xa
nam luc » nang luc, nhan luc, nam thuc

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 ((nang xa) or (lang xa)) hoi. hieu van nam luc van hanh di ((cuu tre) or (cau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty ((nang xa) OR (lang xa)) hoi. hieu van nam luc van hanh di ((cuu tre) OR (cau tren)).
• Adding a wildcard symbol may retrieve word variants: tu sach ty ((nang xa) or (lang xa)) hoi. hieu van nam luc van hanh di ((cuu tre) or (cau tren))*.