Perhaps you should try some spelling variations:
cam thuc » cam thu, can thuc, cay thuc
nam thuc » nam thuoc, nam thu, nam tu
tu sach » thu sach, su sach, te sach
sach ly » sach y, sach lo, sach ty
ly nang » ky nang, ly hang, ly vang
cao hoc » co hoc, cho hoc, chat hoc
hieu va » lieu va, hieu qua
va hanh » van hanh, va thanh, va danh
su tien » su kien, su hien, tu tieng
vi su » va su, ve su, ki su

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ly nang cao hoc. hieu va ((((cam thuc) OR (nam thuc))) or (am thuc)) va hanh vi su tien~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ly nang cao hoc. hieu va ((((cam thuc) OR (nam thuc))) OR (am thuc)) va hanh vi su tien.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ly nang cao hoc. hieu va ((((cam thuc) OR (nam thuc))) or (am thuc)) va hanh vi su tien".
• Adding a wildcard symbol may retrieve word variants: tu sach ly nang cao hoc. hieu va ((((cam thuc) OR (nam thuc))) or (am thuc)) va hanh vi su tien*.