Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
luu van » cuu van, luan van, luu hanh
luc van » luoc van, duc van, luc va
hieu ve » hieu va, hieu van
cao hoc » co hoc, cho hoc, chat hoc
ty nang » ky nang, ty hang, ly nang
cua cay » cua cac
ve cau » ke cau, va cau, ve cac
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: toc sach ((ty nang) or (ty xang)) cao hoc. hieu ve cau ((luc van) OR (luu van)) hanh vi cua cay~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ((ty nang) OR (ty xang)) cao hoc. hieu ve cau ((luc van) OR (luu van)) hanh vi cua cay*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ((ty nang) or (ty xang)) cao hoc. hieu ve cau ((luc van) OR (luu van)) hanh vi cua cay*".