Perhaps you should try some spelling variations:
duc manh » suc manh, duc anh, duc minh
tu sach » thu sach, su sach, te sach
ly hang » ly quang
hieu va » lieu va, hieu qua
duc van » duc va, duc tan, duc phan
hanh va » hang va, hanh vi
cuu tre » cua tre, cau tren, cau treo
va cam » va cham, va cac, va cao
va cuu » va cau, va chu, va huu

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 ((ky nang) or (ly hang)) xa hoi. hieu va cam ((duc van) or (duc manh)) hanh va cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky nang) OR (ly hang)) xa hoi. hieu va cam ((duc van) OR (duc manh)) hanh va cuu tre.
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky nang) or (ly hang)) xa hoi. hieu va cam ((duc van) or (duc manh)) hanh va cuu tre*.