Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
dang xay » dang van, van xay
thuc van » thuc dan, thuc va, thuc hanh
xay hoi » xa hoi, tay hoi, cay phoi
hieu le » hieu ve, hieu he, hieu ly
y dang » ky dang, 2 dang, _ dang
cua tu » cua tuc, cua cu, cua te
cua su » qua su
le na » le nam, le va, le ta

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 y dang xay hoi. hieu le na ((thuc van) or (thuc vat)) hanh vi ((cua tu) OR (cua su))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach y dang xay hoi. hieu le na ((thuc van) OR (thuc vat)) hanh vi ((cua tu) OR (cua su)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach y dang xay hoi. hieu le na ((thuc van) or (thuc vat)) hanh vi ((cua tu) OR (cua su))".
• Adding a wildcard symbol may retrieve word variants: toc sach y dang xay hoi. hieu le na ((thuc van) or (thuc vat)) hanh vi ((cua tu) OR (cua su))*.