Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
van hanh » van thanh, ban hanh, van anh
xang cho » sang cho, hang cho, tang cho
cac luc » cau luc, coc luc, cac nuoc
vai cua » dai cua, hai cua, lai cua
luc van » luoc van, luu van, duc van
hieu ve » hieu va, hieu van
cho hoc » co hoc, khoa hoc
ve cac » va cac, vien cac
vi 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) or (hoc sach)) ty xang cho hoc. hieu ve cac luc van hanh ((vi cua) OR (vai cua)) cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ty xang cho hoc. hieu ve cac luc van hanh ((vi cua) OR (vai cua)) cau*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) ty xang cho hoc. hieu ve cac luc van hanh ((vi cua) OR (vai cua)) cau*".