Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
cua duc » cua tuc, cua nuoc, cua quoc
duc van » duc va, duc tan, duc manh
cac duc » cac du, cao duc, cac dac
hieu ve » hieu va, hieu van
sach v » sach va, sach y, sach 2
ve cac » va cac, vien cac
ma hoi » mai hoi, ma hoa, me hoi
v nang » va nang, vu nang, van nang
cua tu » cua tuc, cua su, cua cu

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 v nang ((ma hoi) or (xa hoi)). hieu ve cac duc van hanh vi ((cua duc) or (cua tu))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach v nang ((ma hoi) OR (xa hoi)). hieu ve cac duc van hanh vi ((cua duc) OR (cua tu)).
• Adding a wildcard symbol may retrieve word variants: toc sach v nang ((ma hoi) or (xa hoi)). hieu ve cac duc van hanh vi ((cua duc) or (cua tu))*.