Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
tu sach » su sach, te sach, tu cach
xay hoi » xa hoi, tay hoi, cay phoi
hieu va » lieu va, hieu qua
dao bai » cao bai, dao hai, dao lai
bai cua » ban cua, dai cua, bai ca
cua tre » cua te, cuu tre, cua triet
y dang » ky dang, 2 dang, b dang
_ dang » _ dan, 2 dang, _ danh
va hoc » van hoc
va dao » ca dao
nuoc » quoc, duoc, ngoc

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)) ((y dang) OR (_ dang)) xay hoi. hieu va hoc nuoc va dao bai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((thu sach) OR (tu sach)) ((y dang) OR (_ dang)) xay hoi. hieu va hoc nuoc va dao bai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((thu sach) or (tu sach)) ((y dang) OR (_ dang)) xay hoi. hieu va hoc nuoc va dao bai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((thu sach) or (tu sach)) ((y dang) OR (_ dang)) xay hoi. hieu va hoc nuoc va dao bai cua tre*.