Perhaps you should try some spelling variations:
nang doc » nang luc
hanh noi » ha noi, hanh vi, nang noi
van hanh » van thanh, ban hanh, van anh
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
noi cua » hoi cua, doi cua, moi cua
nang ra » nang ma, lang ra, nang ro
va tuc » va thuc, va tac, va thuoc
cua te » cua tu
va tu » va su

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 doc) or (nang ra)) hoi. hieu qua ((va tuc) or (va tu)) van hanh noi cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky ((nang doc) OR (nang ra)) hoi. hieu qua ((va tuc) OR (va tu)) van hanh noi cua te.
• Adding a wildcard symbol may retrieve word variants: tu sach ky ((nang doc) or (nang ra)) hoi. hieu qua ((va tuc) or (va tu)) van hanh noi cua te*.