Perhaps you should try some spelling variations:
hoc sach » hoc sinh, hoc cac, hoc anh
tang van » dang van, hoang van, trong van
cac thuc » cach thuc, cac thu, can thuc
dao dinh » do dinh, dao minh, dao tinh
dinh cau » dinh chau, dinh cuu, dinh cu
cau tren » cu tren, dau tren, ca tren
sach ky » sac ky, sach y, sach ty
hieu ve » hieu van
hieu va » lieu va, hieu qua
thuc ca » thuc cua, thuc can, thuc cao

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 ((tang van) or (nang cao)) hoi. ((hieu ve) or (hieu va)) cac thuc ca dao dinh cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sach ky ((tang van) OR (nang cao)) hoi. ((hieu ve) OR (hieu va)) cac thuc ca dao dinh cau tren.
• Adding a wildcard symbol may retrieve word variants: hoc sach ky ((tang van) or (nang cao)) hoi. ((hieu ve) or (hieu va)) cac thuc ca dao dinh cau tren*.