Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
va triet » va thiet, va trien, ve triet
va hanh » van hanh, va thanh, va danh
y nang » ky nang, ly nang, v nang
ve cac » va cac, vien cac
cua tu » cua tuc, cua su, cua cu
x hoi » xa hoi, o hoi, x ho
va co » vo co

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 y nang x hoi. hieu ((va co) or (ve cac)) duc va hanh vi ((cua tu) or (va triet))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach y nang x hoi. hieu ((va co) OR (ve cac)) duc va hanh vi ((cua tu) OR (va triet)).
• Adding a wildcard symbol may retrieve word variants: doc sach y nang x hoi. hieu ((va co) or (ve cac)) duc va hanh vi ((cua tu) or (va triet))*.