Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ban hanh » ban hang
sach ky » sac ky, sach y, sach ty
hieu ve » hieu va, hieu van
cac duc » cac du, cao duc, cac dac
duc ban » duc tan, duc van, dua ban
cua tuc » cua duc, cua thuoc, luat tuc
ve cac » va cac, vien cac
cua tu » cua su, cua cu, cua te

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sach ky ((mang may) or (nang cao)) hoi. hieu ve cac duc ban hanh vi ((cua tu) or (cua tuc))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky ((mang may) OR (nang cao)) hoi. hieu ve cac duc ban hanh vi ((cua tu) OR (cua tuc)).
• Adding a wildcard symbol may retrieve word variants: toc sach ky ((mang may) or (nang cao)) hoi. hieu ve cac duc ban hanh vi ((cua tu) or (cua tuc))*.