Perhaps you should try some spelling variations:
nam thuc » nam thuoc, am thuc, nam thu
va thanh » gia thanh, ban thanh, va tinh
va triet » va trien, ve triet, cua triet
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
va hanh » van hanh, va danh, ban hanh
ve nam » he nam, va nam, le nam
x hoi » xa hoi, o hoi, x ho
thiet » thieu

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ky nang x hoi. hieu ve nam thuc ((va hanh) OR (va thanh)) vai ((va triet) or (va thiet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang x hoi. hieu ve nam thuc ((va hanh) OR (va thanh)) vai ((va triet) OR (va thiet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky nang x hoi. hieu ve nam thuc ((va hanh) OR (va thanh)) vai ((va triet) or (va thiet))".
• Adding a wildcard symbol may retrieve word variants: su sach ky nang x hoi. hieu ve nam thuc ((va hanh) OR (va thanh)) vai ((va triet) or (va thiet))*.