Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
cua dang » cua cong, cua ban
sach cua » mach cua, cach cua, sac cua
cua tre » cua te, cuu tre, cua triet
va chat » van chat, va phat, cao chat
hieu va » lieu va, hieu qua
dang xa » dang xay, lang xa, dang ha
xuc va » duc va, luc va, xac va
tuc va » thuc va, truc va, tuc xa
dan vi » doan vi, dan va, gan vi

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sach cua dang xa hoi. hieu va chat ((xuc va) OR (tuc va)) ((dan vi) or (don vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach cua dang xa hoi. hieu va chat ((xuc va) OR (tuc va)) ((dan vi) OR (don vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sach cua dang xa hoi. hieu va chat ((xuc va) OR (tuc va)) ((dan vi) or (don vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: hoc sach cua dang xa hoi. hieu va chat ((xuc va) OR (tuc va)) ((dan vi) or (don vi)) cua tre*.