Perhaps you should try some spelling variations:
tan hanh » tan thanh, tang hanh, toan hanh
dua tren » dung tren
cau treo » cau theo, cau tren, cau triet
sach ty » sach y, sach thu, xach tay
sach tu » sach thu, cach tu, sach uu
tang xa » trang xa, tang ma, lang xa
qua cam » qua cham, qua cac, qua ca
cam duc » cam xuc, cao duc, pham duc

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

• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sach tu)) tang xa hoi. hieu qua cam duc tan hanh vi ((dua tren) OR (cau treo))~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach ty) OR (sach tu)) tang xa hoi. hieu qua cam duc tan hanh vi ((dua tren) or (cau treo))~".
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) OR (sach tu)) tang xa hoi. hieu qua cam duc tan hanh vi ((dua tren) or (cau treo))*.