Perhaps you should try some spelling variations:
ban thanh » ban hanh, ban hang
cham tuc » nham thuc, pham thuc, tham thuc
va thanh » gia thanh, va tinh, le thanh
hieu vu » hieu va, hieu ve, hieu su
vu cham » va cham, vu kham, tu cham
sach ty » sach y, sach tu, sach thu
cao hoi » cau hoi, co hoi, cao hoc
ty nang » ky nang, ty xang, ty hang
tu sach » thu sach, su sach, te sach
va vai » va bai, va van, va dai
va va » va van, va vua, va vat

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 ty nang cao hoi. hieu vu cham tuc ((va thanh) OR (ban thanh)) ((va va) or (va vai)) thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ty nang cao hoi. hieu vu cham tuc ((va thanh) OR (ban thanh)) ((va va) OR (va vai)) thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ty nang cao hoi. hieu vu cham tuc ((va thanh) OR (ban thanh)) ((va va) or (va vai)) thiet".
• Adding a wildcard symbol may retrieve word variants: tu sach ty nang cao hoi. hieu vu cham tuc ((va thanh) OR (ban thanh)) ((va va) or (va vai)) thiet*.