Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
truc van » truc va, thuc van, truc ban
cam truc » cau truc, nam truc, lam truoc
hieu van » hieu va, thien van, lieu va
su sach » vu sach
van cam » van nam, van lam, van cau
cua tre » cua te, cuu tre, cua triet
so sach » so sanh, bo sach, co sach
nang ma » tang ma, sang ma, nang cao
vi cua » vai cua, di cua

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((su sach) OR (so sach)) v ((nang x) OR (nang ma)) hoi. hieu van cam truc van hanh vi cua tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((su sach) OR (so sach)) v ((nang x) or (nang ma)) hoi. hieu van cam truc van hanh vi cua tre~".
• Adding a wildcard symbol may retrieve word variants: ((su sach) OR (so sach)) v ((nang x) or (nang ma)) hoi. hieu van cam truc van hanh vi cua tre*.