Perhaps you should try some spelling variations:
van hanh » van thanh, ban hanh, van anh
cua tre » cua te, cua triet, dua tren
sach ky » sach y, sach ty, sach kem
hieu ve » hieu va, hieu van
cuu tre » cau tren, cau treo
sac ky » cac ky, sai ky
cac bo » bac bo, cac co
bo van » vo van, so van, do van
ve cac » va cac, vien cac
x hoi » xa hoi, o hoi, x ho

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

• Performing a fuzzy search may retrieve terms with similar spellings: su ((sach ky) or (sac ky)) nang x hoi. hieu ve cac bo van hanh vi ((cua tre) or (cuu tre))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su ((sach ky) OR (sac ky)) nang x hoi. hieu ve cac bo van hanh vi ((cua tre) OR (cuu tre)).
• Adding a wildcard symbol may retrieve word variants: su ((sach ky) or (sac ky)) nang x hoi. hieu ve cac bo van hanh vi ((cua tre) or (cuu tre))*.