Perhaps you should try some spelling variations:
sach hay » sach han, sach ha, sach vay
sach nay » sach vay, sach nang, sach ngan
van hanh » van thanh, ban hanh, van anh
tang ma » mang may, tang van
hieu va » lieu va, hieu qua
cao tuc » dao tuc, cao duc, cao suc
tuc van » thuc van, truc van, tuc va
ca tren » cau tren, cu tren, la tren
ma hoi » mai hoi, xa hoi, ma hoa
va cao » va cac, va co, va dao
vi ca » vit ca, li ca, va ca

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach hay) OR (sach nay)) tang ma hoi. hieu va cao tuc van hanh vi ca tren~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su ((sach hay) OR (sach nay)) tang ma hoi. hieu va cao tuc van hanh vi ca tren".
• Adding a wildcard symbol may retrieve word variants: su ((sach hay) OR (sach nay)) tang ma hoi. hieu va cao tuc van hanh vi ca tren*.