Perhaps you should try some spelling variations:
van thanh » ban thanh, van tuan
toc sach » hoc sach, doc sach, thuoc sach
thuc van » thuc vat, thuc dan, thuc va
cam thuc » am thuc, nam thuc, cam thu
hai cua » thai cua, hoi cua, lai cua
hieu ve » hieu va, hieu van
tay hoi » tay ho, tao hoi, tay thai
xay hoi » xa hoi, cay phoi, gay thoi
sach o » sach lo, sac o, sach y
ve cam » ve cham, ve cac, va cam
o dang » xo dang, do dang, so dang

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: toc sach o dang ((xay hoi) OR (tay hoi)). hieu ve cam thuc van thanh ((hai cua) OR (dai cua)) tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach o dang ((xay hoi) OR (tay hoi)). hieu ve cam thuc van thanh ((hai cua) or (dai cua)) tre~".
• Adding a wildcard symbol may retrieve word variants: toc sach o dang ((xay hoi) OR (tay hoi)). hieu ve cam thuc van thanh ((hai cua) or (dai cua)) tre*.