Perhaps you should try some spelling variations:
su triet » su viet, su tien, 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 day » cac dan, cac dai, cac cay
va hanh » van hanh, va thanh, ban hanh
va danh » va dinh, va dan, dia danh
sac ky » cac ky, sai ky
doi su » oi su, don su, voi 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 ky) or (sac ky)) nang xa hoi. hieu va cac day ((va hanh) OR (va danh)) doi su triet~.
• 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 day ((va hanh) OR (va danh)) doi su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sac ky)) nang xa hoi. hieu va cac day ((va hanh) OR (va danh)) doi su triet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang xa hoi. hieu va cac day ((va hanh) OR (va danh)) doi su triet*.