Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
hanh vai » hanh vi, hanh tai, hanh van
su triet » su viet, su tien, ve triet
sach ky » sac ky, sach y, sach ty
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
hanh va » hang va, hanh vi
ve cac » va cac, vien cac
cac so » cac co, cac bo, cac ho
so van » su van, vo van

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky nang xa hoi. hieu ve cac so van ((hanh vai) or (hanh va)) su triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang xa hoi. hieu ve cac so van ((hanh vai) OR (hanh va)) su triet.
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang xa hoi. hieu ve cac so van ((hanh vai) or (hanh va)) su triet*.