Perhaps you should try some spelling variations:
su triet » su viet, ve triet
sach ky » sach y, sach ty, sach kem
nang xa » nang x, lang xa, nang ma
hieu va » lieu va, hieu qua
cac duc » cac du, cao duc, cac dac
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
su tien » su kien, su hien, tu tieng
sac ky » cac ky, sai ky

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 ky) or (sac ky)) nang xa hoi. hieu va cac duc va hanh di ((su triet) or (su tien))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang xa hoi. hieu va cac duc va hanh di ((su triet) OR (su tien)).
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang xa hoi. hieu va cac duc va hanh di ((su triet) or (su tien))*.