Perhaps you should try some spelling variations:
sach ky » sac ky, sach y, sach kem
va hanh » van hanh, va thanh, va danh
hieu le » hieu ve, hieu he, hieu ly
mai hoi » mai khoi, dai hoi, lai hoi
cuu tre » cua tre, cau tren, cau treo
sach ty » sach y, sach tu, sach thu
ma hoi » xa hoi, ma hoa, me hoi
le dat » le dan, de dat, le dac
vi cuu » vi luu, vinh cuu
nuoc » quoc, duoc, ngoc

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