Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
hieu van » hieu va, thien van, lieu va
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va
thuc va » thuc vat, thuc dan, thuc day
va danh » va dinh, va dan, va hanh
danh va » doanh va, hanh va, anh va
va cua » va chua, via cua, ca cua
x hoi » xa hoi, o hoi, 5 hoi

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 nang ((x hoi) OR (x ho)). ((hieu ve) or (hieu van)) am thuc va danh va cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang ((x hoi) OR (x ho)). ((hieu ve) OR (hieu van)) am thuc va danh va cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ky nang ((x hoi) OR (x ho)). ((hieu ve) or (hieu van)) am thuc va danh va cua viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang ((x hoi) OR (x ho)). ((hieu ve) or (hieu van)) am thuc va danh va cua viet*.