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