Perhaps you should try some spelling variations:
dat thanh » dao thanh, dat khanh, dang thanh
nam thuc » nam thuoc, am thuc, nam thu
da thanh » dao thanh, dam thanh, dan thanh
hieu van » hieu va, thien van, lieu va
doi cuu » doi cua, doi cuoc
toc sac » toc sach, toc san, hoc sach
nang xa » nang x, lang xa, mang xa
nang ma » tang ma, sang ma, nang cao
cuu tre » cua tre, cau tren, cau treo
sac ky » cac ky, sai ky

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

• Performing a fuzzy search may retrieve terms with similar spellings: toc sac ky ((nang xa) OR (nang ma)) hoi. hieu van nam thuc ((da thanh) or (dat thanh)) doi cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sac ky ((nang xa) OR (nang ma)) hoi. hieu van nam thuc ((da thanh) OR (dat thanh)) doi cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sac ky ((nang xa) OR (nang ma)) hoi. hieu van nam thuc ((da thanh) or (dat thanh)) doi cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sac ky ((nang xa) OR (nang ma)) hoi. hieu van nam thuc ((da thanh) or (dat thanh)) doi cuu tre*.