Perhaps you should try some spelling variations:
cham thuc » nham thuc, pham thuc, tham thuc
toc sach » hoc sach, doc sach, thuoc sach
cua viet » ca viet, hoa viet, cua vat
sach ty » sach y, sach tu, sach thu
ty nang » ky nang, ty xang, ty hang
cao hoi » cau hoi, cao hoc, tao hoi
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
thuc va » thuc vat, thuc dan, thuc day
dinh vi » dinh ve, dinh viet, dinh tri
co hoi » co hoc, co loi

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ty nang ((cao hoi) OR (co hoi)). hieu ve cham thuc va ((dinh vi) or (chinh tri)) cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty nang ((cao hoi) OR (co hoi)). hieu ve cham thuc va ((dinh vi) OR (chinh tri)) cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty nang ((cao hoi) OR (co hoi)). hieu ve cham thuc va ((dinh vi) or (chinh tri)) cua viet".
• Adding a wildcard symbol may retrieve word variants: toc sach ty nang ((cao hoi) OR (co hoi)). hieu ve cham thuc va ((dinh vi) or (chinh tri)) cua viet*.