Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
tan hanh » tan thanh, tang hanh, toan hanh
va triet » va thiet, va trien, ve triet
sach ky » sac ky, sach y, sach ty
va cao » va co, va dao, va bao
cua cu » cua chu, cua cau, cua su
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ky nang x hoi. hieu ((va cao) or (va cac)) duc tan hanh vi ((cua cu) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky nang x hoi. hieu ((va cao) OR (va cac)) duc tan hanh vi ((cua cu) OR (va triet)).
• Adding a wildcard symbol may retrieve word variants: doc sach ky nang x hoi. hieu ((va cao) or (va cac)) duc tan hanh vi ((cua cu) or (va triet))*.