Perhaps you should try some spelling variations:
khoa hoc » hoa hoc
van hanh » van thanh, ban hanh, van anh
toc sach » hoc sach, doc sach, thuoc sach
luoc van » luoc can, luoc va, luc van
cac luoc » cac nuoc, cac cuoc, cac quoc
hieu va » lieu va, hieu qua
cua cay » cua cac
cho hoc » co hoc
ty nang » ky nang, ty xang, ty hang
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: ((te sach) OR (toc sach)) ty nang ((cho hoc) OR (khoa hoc)). hieu va cac luoc van hanh vi cua cay~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ty nang ((cho hoc) or (khoa hoc)). hieu va cac luoc van hanh vi cua cay~".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ty nang ((cho hoc) or (khoa hoc)). hieu va cac luoc van hanh vi cua cay*.