Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hanh tai » thanh tai, hang tai, han tai
so triet » su triet, so thiet, bo triet
su sach » so sach, vu sach
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
ve bac » ve bao, ve cac, ve ban
bo van » vo van, so van, do van
tai so » tai sao, dai so, tai co
x hoi » o hoi, x ho, 5 hoi

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 ky nang ((x hoi) or (xa hoi)). hieu ve bac bo van hanh tai so triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ky nang ((x hoi) OR (xa hoi)). hieu ve bac bo van hanh tai so triet.
• Adding a wildcard symbol may retrieve word variants: su sach ky nang ((x hoi) or (xa hoi)). hieu ve bac bo van hanh tai so triet*.