Perhaps you should try some spelling variations:
cac thuc » cach thuc, cac thu, can thuc
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, tu cach, vu sach
te sach » toc sach
su sach » so sach, vu sach
cao hoi » cau hoi, co hoi, cao hoc
hieu ve » hieu va, hieu van
thuc va » thuc vat, thuc dan, thuc day
ve cac » va cac, vien cac
va dan » ca dan, va dao, va dau
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) OR (te sach))) OR (su sach)) ky nang cao hoi. hieu ve cac thuc va dan ca cau tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((((tu sach) OR (te sach))) or (su sach)) ky nang cao hoi. hieu ve cac thuc va dan ca cau tren~".
• Adding a wildcard symbol may retrieve word variants: ((((tu sach) OR (te sach))) or (su sach)) ky nang cao hoi. hieu ve cac thuc va dan ca cau tren*.