Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
dang xay » dang van, van xay
cau treo » cau tren, cau triet, cau trieu
nam thuc » nam thuoc, am thuc, nam thu
cau theo » cau thi, cau tao
hoc sach » hoc sinh, hoc cac, hoc anh
ky dang » ky nang, ky danh
xay hoi » xa hoi, tay hoi, cay phoi
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
dao bai » cao bai, dao hai, dao lai
va dao » ca dao
va nam » van nam, ha nam, va nay

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) or (hoc sach)) ky dang xay hoi. hieu va nam thuc va dao bai ((cau treo) OR (cau theo))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ky dang xay hoi. hieu va nam thuc va dao bai ((cau treo) OR (cau theo)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) ky dang xay hoi. hieu va nam thuc va dao bai ((cau treo) OR (cau theo))".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) ky dang xay hoi. hieu va nam thuc va dao bai ((cau treo) OR (cau theo))*.