Perhaps you should try some spelling variations:
thanh dai » thanh hai, thanh tai, thanh dat
van thanh » ban thanh, van tuan
thu sach » thuat sach, thuoc sach, thu hoach
cham so » cham soc, cham o, ham so
vu cham » va cham, vu kham, tu cham
hieu vu » hieu va, hieu ve, hieu su
mai hoi » mai khoi, dai hoi, lai hoi
tu sach » su sach, te sach, tu cach
cua tre » cua te, cuu tre, cua triet
ma hoi » xa hoi, ma hoa, me hoi
so van » su van, vo van

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((thu sach) OR (tu sach)) ky nang ((ma hoi) or (mai hoi)). hieu vu cham so van thanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (tu sach)) ky nang ((ma hoi) OR (mai hoi)). hieu vu cham so van thanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) OR (tu sach)) ky nang ((ma hoi) or (mai hoi)). hieu vu cham so van thanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) OR (tu sach)) ky nang ((ma hoi) or (mai hoi)). hieu vu cham so van thanh dai cua tre*.