Perhaps you should try some spelling variations:
khoa hoi » khoan hoi, khoa hoc, khoa doi
cuu thuc » cuu tac
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
hieu ve » hieu va, hieu van
tu sach » thu sach, su sach, tu cach
hoa hoi » hoa hoc, hoa doi, hoc hoi
ky hang » ky nang, ly hang, ky dang
te sach » toc sach
cua tre » cua te, cuu tre, cua triet
ve cuu » ve cau, ve chu, ve cua
vi cua » vai cua, di cua

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

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