Perhaps you should try some spelling variations:
dua tren » dung tren
ban hang » ngan hang
vu sach » vu bach, su sach, vu khach
duc ban » duc tan, duc van, dua ban
hang vi » hang va, hanh vi, hang di
van bao » van ban
nang ma » tang ma, sang ma, nang cao
cuu tre » cua tre, cau tren, cau treo
y nang » ky nang, ly nang, v nang
ma hoi » mai hoi, xa hoi, ma hoa

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

• Performing a fuzzy search may retrieve terms with similar spellings: vu sach y nang ma hoi. hieu ((van dao) or (van bao)) duc ban hang vi ((dua tren) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach y nang ma hoi. hieu ((van dao) OR (van bao)) duc ban hang vi ((dua tren) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: vu sach y nang ma hoi. hieu ((van dao) or (van bao)) duc ban hang vi ((dua tren) or (cuu tre))*.