Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
dua tren » dung tren
van hanh » van thanh, ban hanh, van anh
duc van » duc va, duc tan, duc manh
cam duc » cam xuc, cao duc, pham duc
van cam » van nam, van lam, van cau
sach tu » sach thu, cach tu, sach ty
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
lang xa » lang ha, dang xay, lang van
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: su sach tu ((lang xa) or (nang ma)) hoi. hieu van cam duc van hanh vi ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach tu ((lang xa) OR (nang ma)) hoi. hieu van cam duc van hanh vi ((dua tren) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: su sach tu ((lang xa) or (nang ma)) hoi. hieu van cam duc van hanh vi ((dua tren) or (cuu tre))*.