Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
ban hanh » ban hang
hieu van » hieu va, thien van, lieu va
tang ma » mang may, tang van
sach ty » sach y, sach tu, sach thu
van hoc » van hoa
hoc duc » hoc duoc, hoc nuoc, hoc thuc
duc ban » duc tan, duc van, dua ban
xang ma » nang ma, sang ma, rang ma
cua tu » cua tuc, cua cu, cua te
cua su » qua su

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 ty ((xang ma) or (tang ma)) hoi. hieu van hoc duc ban hanh vi ((cua tu) or (cua su))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((xang ma) OR (tang ma)) hoi. hieu van hoc duc ban hanh vi ((cua tu) OR (cua su)).
• Adding a wildcard symbol may retrieve word variants: toc sach ty ((xang ma) or (tang ma)) hoi. hieu van hoc duc ban hanh vi ((cua tu) or (cua su))*.