Perhaps you should try some spelling variations:
thanh cha » thanh ha, thanh nha, thanh phan
thanh ca » thanh cac, thanh ha, thanh va
vu sach » vu bach, su sach, vu khach
cac luc » cau luc, coc luc, cac nuoc
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
van hoe » van hoa, van hoc, van hieu
van hoi » van hoa, van hoc, van loi
ky lang » ky nang, ky dang, ky tang
luc va » duc va, tuc va, loc va
ve cac » va cac, vien cac

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 ((van hoi) or (van hoe)). hieu ve cac luc va ((thanh ca) OR (thanh cha)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sach ky lang ((van hoi) OR (van hoe)). hieu ve cac luc va ((thanh ca) OR (thanh cha)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sach ky lang ((van hoi) or (van hoe)). hieu ve cac luc va ((thanh ca) OR (thanh cha)) cua tre*".