Perhaps you should try some spelling variations:
sach dat » sach danh, sach bai, sach xa
sach dao » lanh dao
van hanh » van thanh, ban hanh, van anh
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac dac
duc van » duc va, duc tan, duc manh
hanh va » hang va, hanh vi
cua tre » cua te, cuu tre, cua triet
va hoi » xa hoi, va hoc, va hoa
ve cac » va cac, vien cac
va cua » va chua, via cua, ca cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach dat) or (sach dao)) nano va hoi. hieu ve cac duc van hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach dat) OR (sach dao)) nano va hoi. hieu ve cac duc van hanh va cua tre.
• Adding a wildcard symbol may retrieve word variants: su ((sach dat) or (sach dao)) nano va hoi. hieu ve cac duc van hanh va cua tre*.