Perhaps you should try some spelling variations:
hieu van » hieu va, thien van, lieu va
cao hoi » cau hoi, co hoi, cao hoc
va hanh » van hanh, va thanh, va danh
tu sach » thu sach, te sach, tu cach
ty nang » ky nang, ty xang, ty hang
su sach » so sach, vu sach
bac su » bac si, ban su, bac tu
bac sy » bac si, bac ky
vi cua » vai cua, di cua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((tu sach) OR (su sach)) ty nang cao hoi. hieu van ((bac su) OR (bac sy)) va hanh vi cua vat~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((tu sach) or (su sach)) ty nang cao hoi. hieu van ((bac su) OR (bac sy)) va hanh vi cua vat~".
• Adding a wildcard symbol may retrieve word variants: ((tu sach) or (su sach)) ty nang cao hoi. hieu van ((bac su) OR (bac sy)) va hanh vi cua vat*.