Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
bac loai » cac loai, lac loai, bac dai
hieu van » hieu va, thien van, lieu va
loai va » loai nam
van bac » van ban, van bao, van hac
lang xa » lang ha, dang xay, lang van
mang xa » mang may, dang xay, mang cua
va dan » ca dan, va dao, va dau
dan vi » doan vi, don vi, dan va
vi cua » vai cua, di cua
cua te » cua tu

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

• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky ((mang xa) OR (lang xa)) hoi. hieu van bac loai va dan vi cua te~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) ky ((mang xa) or (lang xa)) hoi. hieu van bac loai va dan vi cua te~".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) ky ((mang xa) or (lang xa)) hoi. hieu van bac loai va dan vi cua te*.