Perhaps you should try some spelling variations:
thanh dat » thanh hai, thanh van, thanh ha
te sach » toc sach
cac dac » cac dan, cac dai, cac bac
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
mai hoi » mai khoi, dai hoi, lai hoi
y nang » ky nang, ly nang, v nang
dac va » duc va, day va, dat va
ma hoi » xa hoi, ma hoa, me hoi
ve cac » va cac, vien cac

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

• If you are trying to use Boolean operators, they must be ALL CAPS: te sach y nang ((ma hoi) OR (mai hoi)). hieu ve cac dac va ((thanh dat) OR (thanh san)) cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "te sach y nang ((ma hoi) OR (mai hoi)). hieu ve cac dac va ((thanh dat) or (thanh san)) cua tre~".
• Adding a wildcard symbol may retrieve word variants: te sach y nang ((ma hoi) OR (mai hoi)). hieu ve cac dac va ((thanh dat) or (thanh san)) cua tre*.