Perhaps you should try some spelling variations:
hanh vii » hanh voi, hanh va, hanh noi
tu sach » thu sach, su sach, te sach
ky lang » ky nang, ky tang, tay lang
ky dang » ky nang, ky danh
man hoi » man hoai, dan hoi, van hoi
hieu ve » hieu va, hieu van
ve pham » vi pham, v pham, ve phan
cua tre » cua te, cuu tre, cua triet

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 lang) OR (ky dang)) man hoi. hieu ve pham duc va ((hanh vii) or (hanh vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky lang) OR (ky dang)) man hoi. hieu ve pham duc va ((hanh vii) OR (hanh vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky lang) OR (ky dang)) man hoi. hieu ve pham duc va ((hanh vii) or (hanh vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky lang) OR (ky dang)) man hoi. hieu ve pham duc va ((hanh vii) or (hanh vi)) cua tre*.