Perhaps you should try some spelling variations:
su triet » su viet, su tien, ve triet
nam thuc » nam thuoc, nam thu, nam tu
hieu van » hieu va, thien van, lieu va
da nang » cam nang, kha nang, cao nang
cao hoi » cau hoi, co hoi, cao hoc
xa nang » va nang, xa nong, ca nang
va hanh » van hanh, va thanh, va danh
hanh di » hanh vi, hanh de, hang di
su sach » so sach, vu sach
di su » doi su, ki su, da su

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 ((xa nang) OR (da nang)) cao hoi. hieu van ((am thuc) or (nam thuc)) va hanh di su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ((xa nang) OR (da nang)) cao hoi. hieu van ((am thuc) OR (nam thuc)) va hanh di su triet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ((xa nang) OR (da nang)) cao hoi. hieu van ((am thuc) or (nam thuc)) va hanh di su triet".
• Adding a wildcard symbol may retrieve word variants: su sach ((xa nang) OR (da nang)) cao hoi. hieu van ((am thuc) or (nam thuc)) va hanh di su triet*.