Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
hoc sach » hoc sinh, hoc cac, hoc anh
te sach » toc sach
dac van » cac van, dao van, dam van
cac dac » cac dan, cac dai, cac bac
hieu va » lieu va, hieu qua
cua cau » cua cac, cua chu, cua cay
ty hang » ly hang, ty xang, thi hang
ma hoi » mai hoi, xa hoi, me hoi
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: ((te sach) or (hoc sach)) ty hang ((ma hoi) OR (ma hoa)). hieu va cac dac van hanh vi cua cau~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (hoc sach)) ty hang ((ma hoi) OR (ma hoa)). hieu va cac dac van hanh vi cua cau.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (hoc sach)) ty hang ((ma hoi) OR (ma hoa)). hieu va cac dac van hanh vi cua cau".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (hoc sach)) ty hang ((ma hoi) OR (ma hoa)). hieu va cac dac van hanh vi cua cau*.