Perhaps you should try some spelling variations:
tan hanh » tan thanh, tang hanh, toan hanh
tu sach » thu sach, su sach, te sach
ky tang » ky dang, kho tang, ky trong
hieu va » lieu va, hieu qua
cam duc » cam xuc, cao duc, pham duc
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
va cam » va cham, va cac, va cao

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach ((ky tang) OR (ky nang)) xa hoi. hieu va cam duc tan hanh vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach ((ky tang) OR (ky nang)) xa hoi. hieu va cam duc tan hanh vi ((cua tre) OR (cuu tre)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach ((ky tang) OR (ky nang)) xa hoi. hieu va cam duc tan hanh vi ((cua tre) or (cuu tre))".
• Adding a wildcard symbol may retrieve word variants: tu sach ((ky tang) OR (ky nang)) xa hoi. hieu va cam duc tan hanh vi ((cua tre) or (cuu tre))*.