Perhaps you should try some spelling variations:
duc manh » suc manh, duc anh, duc minh
tu sach » thu sach, su sach, te sach
hanh va » hang va, hanh vi
duc van » duc va, duc tan, duc phan
hieu va » lieu va, hieu qua
ly hang » ly quang
ly nang » ky nang, ly vang, ly quang
cua tre » cua te, cuu tre, cua triet
va cam » va cham, va cac, va cao
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: tu sach ((ly nang) or (ly hang)) xa hoi. hieu va cam ((duc van) OR (duc manh)) hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ly nang) OR (ly hang)) xa hoi. hieu va cam ((duc van) OR (duc manh)) hanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ly nang) or (ly hang)) xa hoi. hieu va cam ((duc van) OR (duc manh)) hanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ly nang) or (ly hang)) xa hoi. hieu va cam ((duc van) OR (duc manh)) hanh va cua tre*.