Perhaps you should try some spelling variations:
va triet » va thiet, va trien, ve triet
su triet » su viet, su tien, ve triet
cac phuc » cau phuc, khac phuc, cach thuc
sang ma » tang ma, sang tao, mang may
hieu va » lieu va, hieu qua
sach ky » sac ky, sach y, sach ty
phuc va » phuc vu, thuc va, chuc va
va hanh » van hanh, va thanh, va danh
hanh ca » hanh cac, hanh cat, hanh cua
nang ma » tang ma, nang cao, mang may
su sach » so sach, vu sach

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 ma) OR (sang ma)) hoi. hieu va cac phuc va hanh ca ((su triet) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky ((nang ma) OR (sang ma)) hoi. hieu va cac phuc va hanh ca ((su triet) OR (va triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ky ((nang ma) OR (sang ma)) hoi. hieu va cac phuc va hanh ca ((su triet) or (va triet))".
• Adding a wildcard symbol may retrieve word variants: su sach ky ((nang ma) OR (sang ma)) hoi. hieu va cac phuc va hanh ca ((su triet) or (va triet))*.