Perhaps you should try some spelling variations:
tu sach » thu sach, su sach, te sach
va hanh » van hanh, va thanh, va danh
vu kham » vu khanh
ve cham » va cham, ve chat, vu cham
sach ky » sac ky, sach y, sach ty
dai hai » dai han, dai tai, dai thao
dai hoi » dai hoc, dai moi
tuc va » thuc va, truc va, tuc xa
vi va » vi van, vai va, vu va
thiet » thieu

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