Perhaps you should try some spelling variations:
day thanh » dao thanh, dat thanh, da thanh
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
thanh do » thanh de, thanh pho, thanh hoa
nam thuc » nam thuoc, nam thu, nam tu
sach ty » sach y, sach tu, sach thu
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
do cua » doi cua, co cua, de cua
cua te » cua tu

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 ((nang xa) OR (nang ma)) hoi. hieu van ((nam thuc) or (am thuc)) day thanh do cua te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ty ((nang xa) OR (nang ma)) hoi. hieu van ((nam thuc) OR (am thuc)) day thanh do cua te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ty ((nang xa) OR (nang ma)) hoi. hieu van ((nam thuc) or (am thuc)) day thanh do cua te".
• Adding a wildcard symbol may retrieve word variants: toc sach ty ((nang xa) OR (nang ma)) hoi. hieu van ((nam thuc) or (am thuc)) day thanh do cua te*.