Perhaps you should try some spelling variations:
thanh vai » thanh hai, thanh van, thanh tai
su sach » so sach, vu sach
vai cua » dai cua, hai cua, lai cua
va chat » van chat, va phat, cao chat
hieu va » lieu va, hieu qua
sach ty » sach y, sach tu, sach thu
ty hang » ly hang, ty xang, thi hang
cua tre » cua te, cuu tre, cua triet
luc va » tuc va, loc va
ca hoi » cua hoi, xa hoi, co hoi

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty hang ((ca hoi) OR (cau hoi)). hieu va chat ((luc va) or (duc va)) thanh vai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty hang ((ca hoi) OR (cau hoi)). hieu va chat ((luc va) OR (duc va)) thanh vai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty hang ((ca hoi) OR (cau hoi)). hieu va chat ((luc va) or (duc va)) thanh vai cua tre".
• Adding a wildcard symbol may retrieve word variants: su sach ty hang ((ca hoi) OR (cau hoi)). hieu va chat ((luc va) or (duc va)) thanh vai cua tre*.