Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dang xay » dang van, van xay
dung hai » dung tai, dung ha, dung sai
dang hai » dang khai, hang hai, dong hai
cua tre » cua te, cuu tre, cua triet
sach ky » sac ky, sach y, sach ty
cao suc » cao su, cao duc
hieu ve » hieu va, hieu van
xay hoi » xa hoi, tay hoi, cay phoi
ky dang » ky nang, ky danh

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky dang xay hoi. hieu ve ((cao suc) or (pham duc)) ban ((dang hai) OR (dung hai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky dang xay hoi. hieu ve ((cao suc) OR (pham duc)) ban ((dang hai) OR (dung hai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky dang xay hoi. hieu ve ((cao suc) or (pham duc)) ban ((dang hai) OR (dung hai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky dang xay hoi. hieu ve ((cao suc) or (pham duc)) ban ((dang hai) OR (dung hai)) cua tre*.