Perhaps you should try some spelling variations:
hanh thai » nhanh thai, hinh thai, anh thai
hanh tai » thanh tai, hang tai, han tai
co sach » bo sach, cuon sach, hoc sach
duc van » duc va, duc tan, duc manh
sach ky » sac ky, sach y, sach ty
van hai » van ha, van chat, van hanh
van hac » van hoc, van ha, van chat
xay hoi » xa hoi, tay hoi, cay phoi
cua tre » cua te, cuu tre, cua triet
ky van » ly van, ty van, ky va

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

• Performing a fuzzy search may retrieve terms with similar spellings: co sach ky van xay hoi. thien ((van hac) OR (van hai)) duc van ((hanh thai) or (hanh tai)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: co sach ky van xay hoi. thien ((van hac) OR (van hai)) duc van ((hanh thai) OR (hanh tai)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "co sach ky van xay hoi. thien ((van hac) OR (van hai)) duc van ((hanh thai) or (hanh tai)) cua tre".
• Adding a wildcard symbol may retrieve word variants: co sach ky van xay hoi. thien ((van hac) OR (van hai)) duc van ((hanh thai) or (hanh tai)) cua tre*.