Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
thanh va » thanh van, hanh va, thanh ha
duc van » duc va, duc tan, duc manh
duc ban » duc tan, dua ban, duc man
tu sach » thu sach, su sach, te sach
hieu vu » hieu va, hieu ve, hieu su
ky dang » ky nang, ky danh
ky lang » ky nang, ky tang, tay lang
vu cham » va cham, vu kham, tu cham
ha hoi » hoa hoi, ha noi, xa hoi
va cua » va chua, via cua, ca cua

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 lang) or (ky dang)) ha hoi. hieu vu cham ((duc ban) OR (duc van)) thanh va cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky dang)) ha hoi. hieu vu cham ((duc ban) OR (duc van)) thanh va cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) or (ky dang)) ha hoi. hieu vu cham ((duc ban) OR (duc van)) thanh va cua viet".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) or (ky dang)) ha hoi. hieu vu cham ((duc ban) OR (duc van)) thanh va cua viet*.