Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
vu khach » vu khanh, vu khac, vay khach
quoc ban » quoc bao, quoc lan, quoc quan
ve triet » va trien, su triet
nang xa » nang x, lang xa, nang ma
hieu ve » hieu va, hieu van
xuc ban » duc ban, cuc ban, xuat ban
ve cac » va cac, vien cac
vi ve » va ve, gi ve, ve ve

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) or (vu khach)) ky nang xa hoi. hieu ve cac ((xuc ban) or (quoc ban)) hanh vi ve triet~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (vu khach)) ky nang xa hoi. hieu ve cac ((xuc ban) OR (quoc ban)) hanh vi ve triet.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (vu khach)) ky nang xa hoi. hieu ve cac ((xuc ban) or (quoc ban)) hanh vi ve triet*.