Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc 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
duc van » duc va, duc tan, duc manh
va cam » va cham, va cao, va cai
cua tu » cua tuc, cua su, cua cu
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 cam) or (va cac)) duc van hanh vi ((cua tu) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky nang x hoi. hieu ((va cam) OR (va cac)) duc van hanh vi ((cua tu) OR (va triet)).
• Adding a wildcard symbol may retrieve word variants: doc sach ky nang x hoi. hieu ((va cam) or (va cac)) duc van hanh vi ((cua tu) or (va triet))*.