Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
ban hang » ngan hang
hieu van » hieu va, thien van, lieu va
vu sach » vu bach, su sach, vu khach
lap cua » lai cua, tap cua, lam cua
van cac » van hac, van cau, van bac
cac duc » cac du, cao duc, cac dac
hoa hoi » khoa hoi, hoa hoc, hoa doi
ky lang » ky dang, ky tang, tay lang
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: vu sach ((ky lang) OR (ky nang)) hoa hoi. hieu van cac duc ((van thanh) or (ban hang)) lap cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ((ky lang) OR (ky nang)) hoa hoi. hieu van cac duc ((van thanh) OR (ban hang)) lap cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ((ky lang) OR (ky nang)) hoa hoi. hieu van cac duc ((van thanh) or (ban hang)) lap cua tre".
• Adding a wildcard symbol may retrieve word variants: vu sach ((ky lang) OR (ky nang)) hoa hoi. hieu van cac duc ((van thanh) or (ban hang)) lap cua tre*.