Perhaps you should try some spelling variations:
cua viet » ca viet, hoa viet, cua vat
van hanh » van thanh, ban hanh, van anh
hanh di » hanh vi, hanh de, hang di
xuc van » duc van, luc van, vuc van
hoc sac » hoc sach, hoc cac, hoc mac
nang ma » sang ma, nang cao, mang may
tang ma » mang may, tang van
ve cham » va cham, ve chat, vu cham
sac ky » cac ky, sai ky
ve cac » va cac, vien cac
di cua » dai cua, doi cua, de cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: hoc sac ky ((nang ma) OR (tang ma)) hoi. hieu ((ve cham) or (ve cac)) xuc van hanh di cua viet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: hoc sac ky ((nang ma) OR (tang ma)) hoi. hieu ((ve cham) OR (ve cac)) xuc van hanh di cua viet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "hoc sac ky ((nang ma) OR (tang ma)) hoi. hieu ((ve cham) or (ve cac)) xuc van hanh di cua viet".
• Adding a wildcard symbol may retrieve word variants: hoc sac ky ((nang ma) OR (tang ma)) hoi. hieu ((ve cham) or (ve cac)) xuc van hanh di cua viet*.