Perhaps you should try some spelling variations:
pham thuc » phap thuc, pham chuc, nham thuc
cau tren » cu tren, dau tren, ca tren
tu sach » thu sach, te sach, tu cach
su sach » so sach, vu sach
cao hoi » cau hoi, co hoi, cao hoc
hieu va » lieu va, hieu qua
va pham » van pham, va phat, va phap
thuc ca » thuc cua, thuc can, thuc cao
ca dan » cac dan, ca dao
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 (su sach)) ky nang cao hoi. hieu va pham thuc ca dan ca cau tren~.
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ky nang cao hoi. hieu va pham thuc ca dan ca cau tren*.