Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
dong hoa » dong hoc, dong co
so sach » bo sach, co sach, hoc sach
hanh va » hang va, hanh vi
xuc van » duc van, luc van, vuc van
cua tre » cua te, cuu tre, cua triet
hoa hoi » khoa hoi, hoa hoc, hoa doi
ky dong » ly dong, ky dang, ky cong
so sanh » do sanh
tu nam » su nam
va cua » va chua, via cua, ca cua
tu cam » tu cham, tu cac, tu can

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((so sach) or (so sanh)) ky dong hoa hoi. hieu ((tu cam) OR (tu nam)) xuc van hanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((so sach) OR (so sanh)) ky dong hoa hoi. hieu ((tu cam) OR (tu nam)) xuc van hanh va cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((so sach) or (so sanh)) ky dong hoa hoi. hieu ((tu cam) OR (tu nam)) xuc van hanh va cua tre".
• Adding a wildcard symbol may retrieve word variants: ((so sach) or (so sanh)) ky dong hoa hoi. hieu ((tu cam) OR (tu nam)) xuc van hanh va cua tre*.