Perhaps you should try some spelling variations:
dan hanh » dang hanh, dan khanh, dan thanh
thuc dan » thuc hanh, hoc dan, thuc vat
tu sach » thu sach, su sach, te sach
sach ky » sac ky, sach y, sach ty
cua tre » cua te, cua triet, dua tren
cuu tre » cau tren, cau treo
tang xa » trang xa, tang ma, lang xa
ky tang » ky nang, ky dang, kho tang
ve cam » ve cham, va cam, ve cai
ve cac » va cac, vien cac

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