Perhaps you should try some spelling variations:
vien dai » hien dai
van hanh » van thanh, ban hanh, van anh
hanh gia » danh gia, thanh gian, hinh giao
su triet » su viet, su tien, ve triet
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
nang so » nang som, nang co, nang ho
duc van » duc va, duc tan, duc manh
so hoc » co hoc, mo hoc, so hoa
ve cac » va cac, vien cac
gia su » gia suc, giao su, gia sa

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 so hoc. hieu ((ve cac) or (vien dai)) duc van hanh gia su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ky nang so hoc. hieu ((ve cac) OR (vien dai)) duc van hanh gia su triet.
• Adding a wildcard symbol may retrieve word variants: tu sach ky nang so hoc. hieu ((ve cac) or (vien dai)) duc van hanh gia su triet*.