Perhaps you should try some spelling variations:
so sach » so sanh, bo sach, co sach
sach ky » sac ky, sach y, sach ty
nang ma » tang ma, sang ma, nang cao
va hanh » van hanh, va thanh, va danh
cuu tre » cau tren, cau treo
cua tre » cua te, cua triet, dua tren
ma hoi » mai hoi, xa hoi, ma hoa
le dat » le dan, de dat, ve dat
le dac » le dan, le duc

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

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