Perhaps you should try some spelling variations:
sach mau » sach dau, sach dao, bach mai
dang dan » dang dang, dang van, dung dan
cam thuc » am thuc, nam thuc, cam thu
sach ky » sac ky, sach y, sach ty
tu sach » thu sach, su sach, te sach
hieu va » lieu va, hieu qua
cao hoi » cau hoi, co hoi, cao hoc
dan dan » ban dan, dao dan, dan dat
va cam » va cham, va cac, va cao
ca cau » cua cau, cac cau, can cau

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang cao hoi. hieu va cam thuc ((dan dan) OR (dang dan)) ((ca cau) OR (sach mau)) tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang cao hoi. hieu va cam thuc ((dan dan) OR (dang dan)) ((ca cau) or (sach mau)) tren~".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang cao hoi. hieu va cam thuc ((dan dan) OR (dang dan)) ((ca cau) or (sach mau)) tren*.