Perhaps you should try some spelling variations:
thu sach » thuat sach, thuoc sach, thu hoach
dang xay » dang van, van xay
tu sach » su sach, te sach, tu cach
dao lai » dao lam, dao hai, dao li
dao bai » cao bai, dao hai, dap bai
hieu va » lieu va, hieu qua
cua tre » cua te, cuu tre, cua triet
xay hoi » xa hoi, tay hoi, cay phoi
va hoc » van hoc
y dang » ky dang, 2 dang, _ dang
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: ((tu sach) OR (thu sach)) y dang xay hoi. hieu va hoc nuoc va ((dao bai) or (dao lai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (thu sach)) y dang xay hoi. hieu va hoc nuoc va ((dao bai) OR (dao lai)) cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) OR (thu sach)) y dang xay hoi. hieu va hoc nuoc va ((dao bai) or (dao lai)) cua tre*".