Perhaps you should try some spelling variations:
dan thanh » dang thanh, danh thanh, ban thanh
dieu cua » dieu tra
nam thuc » nam thuoc, am thuc, nam thu
thuc dan » thuc hanh, hoc dan, thuc vat
nang xa » lang xa, nang ma, mang xa
hieu ve » hieu va, hieu van
vu sac » vu sach, vu san, va sac
de cua » le cua, te cua
ve nam » he nam, va nam, le nam
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: vu sac ky ((nang xa) OR (nang x)) hoi. hieu ve nam thuc dan thanh ((de cua) or (dieu cua)) te~.
• If you are trying to use Boolean operators, they must be ALL CAPS: vu sac ky ((nang xa) OR (nang x)) hoi. hieu ve nam thuc dan thanh ((de cua) OR (dieu cua)) te.
• The words AND, OR and NOT may confuse the search; try adding quotes: "vu sac ky ((nang xa) OR (nang x)) hoi. hieu ve nam thuc dan thanh ((de cua) or (dieu cua)) te".
• Adding a wildcard symbol may retrieve word variants: vu sac ky ((nang xa) OR (nang x)) hoi. hieu ve nam thuc dan thanh ((de cua) or (dieu cua)) te*.