Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
nam thuc » nam thuoc, nam tu
danh xay » dang xay, manh xay, anh xay
cau tren » cu tren, dau tren, ca tren
xay hoi » xa hoi, tay hoi, cay phoi
ky danh » ky anh, ky dang
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
dan vai » dan va, dan tai, dan vat
vai cau » va cau, van cau, vai cac
ca dan » cac dan, ca dao

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 ky danh xay hoi. hieu va ((((nam thuc) or (nam thu))) or (am thuc)) ca dan vai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky danh xay hoi. hieu va ((((nam thuc) OR (nam thu))) OR (am thuc)) ca dan vai cau tren.
• Adding a wildcard symbol may retrieve word variants: hoc sach ky danh xay hoi. hieu va ((((nam thuc) or (nam thu))) or (am thuc)) ca dan vai cau tren*.