Perhaps you should try some spelling variations:
hai trac » hoi trac, khai thac, thai tran
dang xay » dang van, van xay
hieu van » hieu va, thien van, lieu va
cua tre » cua te, cuu tre, cua triet
va hanh » van hanh, va thanh, va danh
trac va » truc va, tac va, thac va
van hai » van ha, van chat, van hanh
nang ma » tang ma, sang ma, nang cao
mang xa » lang xa, mang may, mang cua
sac ky » cac ky, sai ky
vi cua » vai cua, di cua
su sac » su sach, su cac, su xac

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sac ky ((((mang xa) OR (dang xay))) or (nang ma)) hoi. hieu van hai trac va hanh vi cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sac ky ((((mang xa) OR (dang xay))) OR (nang ma)) hoi. hieu van hai trac va hanh vi cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sac ky ((((mang xa) OR (dang xay))) or (nang ma)) hoi. hieu van hai trac va hanh vi cua tre*".