Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
tao nano » tao nganh, cao nang, tao cao
su sach » so sach
hanh va » hang va, hanh vi
xuc van » duc van, luc van, vuc van
cua tre » cua te, cuu tre, cua triet
nano xa » nano va, nano bac, nano cau
vu sach » vu bach, vu khach
va cua » va chua, via cua, ca cua
va cam » va cham, va cao, va cai

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

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