Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
sach ky » sach y, sach ty, sach kem
hanh va » hang va, hanh vi
xuc van » duc van, luc van, vuc van
va chat » van chat, va phat, cao chat
ve chat » van chat
nang ma » tang ma, sang ma, nang cao
ma hoi » mai hoi, xa hoi, ma hoa
sac ky » cac ky, sai ky
va va » va van, va vua, va vai
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) or (sac ky)) nang ma hoi. hieu ((ve chat) OR (va chat)) xuc van hanh va va thiet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ky) OR (sac ky)) nang ma hoi. hieu ((ve chat) OR (va chat)) xuc van hanh va va thiet.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ky) or (sac ky)) nang ma hoi. hieu ((ve chat) OR (va chat)) xuc van hanh va va thiet".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ky) or (sac ky)) nang ma hoi. hieu ((ve chat) OR (va chat)) xuc van hanh va va thiet*.