Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
va triet » va thiet, va trien, ve triet
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
xuc van » duc van, luc van, vuc van
ve cam » ve cham, ve cac, va cam
cua te » cua tu
x hoi » xa hoi, x ho, 5 hoi
o hoi » co hoi, o hoc, o hai

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 ((x hoi) OR (o hoi)). hieu ve cam xuc van hanh vi ((cua te) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky nang ((x hoi) OR (o hoi)). hieu ve cam xuc van hanh vi ((cua te) OR (va triet)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky nang ((x hoi) OR (o hoi)). hieu ve cam xuc van hanh vi ((cua te) or (va triet))".
• Adding a wildcard symbol may retrieve word variants: toc sach ky nang ((x hoi) OR (o hoi)). hieu ve cam xuc van hanh vi ((cua te) or (va triet))*.