Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
va thanh » gia thanh, ban thanh, va tinh
cham tuc » nham thuc, pham thuc, tham thuc
hieu ve » hieu va, hieu van
ve cham » va cham, ve chat, vu cham
nang co » nang cao, nang doc, nang noi
bo sach » co sach, hoc sach
co hoi » co hoc, co loi
tuc va » thuc va, truc va, tuc xa
di dau » doi dau, bi dau, di cau
di du » li du

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) or (bo sach)) ky nang co hoi. hieu ve cham tuc va thanh ((di dau) OR (di du)) tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (bo sach)) ky nang co hoi. hieu ve cham tuc va thanh ((di dau) OR (di du)) tren.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (bo sach)) ky nang co hoi. hieu ve cham tuc va thanh ((di dau) OR (di du)) tren".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (bo sach)) ky nang co hoi. hieu ve cham tuc va thanh ((di dau) OR (di du)) tren*.