Perhaps you should try some spelling variations:
toc sach » doc sach, thuoc sach, nuoc sach
hoc sach » hoc sinh, hoc cac, hoc anh
luc van » luoc van, luu van, duc van
xuc van » duc van, vuc van, xuc ban
va chat » van chat, va phat, cao chat
hieu va » lieu va, hieu qua
tang ma » mang may, tang van
ty tang » tay tang, ty xang, ty hang
ma hoi » mai hoi, xa hoi, ma hoa
vi cua » vai cua, di cua
cua cu » cua chu, cua cau, cua su

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 tang ma hoi. hieu va chat ((xuc van) OR (luc van)) hanh vi cua cu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (hoc sach)) ty tang ma hoi. hieu va chat ((xuc van) OR (luc van)) hanh vi cua cu.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (hoc sach)) ty tang ma hoi. hieu va chat ((xuc van) OR (luc van)) hanh vi cua cu".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (hoc sach)) ty tang ma hoi. hieu va chat ((xuc van) OR (luc van)) hanh vi cua cu*.