Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
van hanh » van thanh, ban hanh, van anh
sach ly » sach y, sach lo, sach ty
tang ma » tang van
hieu ve » hieu va, hieu van
cac dac » cac dan, cac dai, cac bac
dac van » cac van, dao van, dam van
hanh di » hanh vi, hanh de, hang di
ve cac » va cac, vien cac
di cua » dai cua, doi cua, de cua
cua tu » cua tuc, cua su, cua cu

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 ly ((mang may) or (tang ma)) hoi. hieu ve cac dac van hanh di cua tu~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ly ((mang may) OR (tang ma)) hoi. hieu ve cac dac van hanh di cua tu*.