Perhaps you should try some spelling variations:
vien cac » vien bach, vien dai, vien da
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
su triet » su viet, su tien, ve triet
su sach » so sach, vu sach
nang xa » nang x, lang xa, nang ma
y nang » ky nang, ly nang, v nang
tu van » tu va
tai su » tai so, tai tu, lai su

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach y nang xa hoi. hieu ((((ve cac) OR (vien cac))) or (va cac)) tu van hanh tai su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach y nang xa hoi. hieu ((((ve cac) OR (vien cac))) OR (va cac)) tu van hanh tai su triet*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach y nang xa hoi. hieu ((((ve cac) OR (vien cac))) or (va cac)) tu van hanh tai su triet*".