Perhaps you should try some spelling variations:
vat danh » va danh, van danh, luat danh
cam thuc » am thuc, nam thuc, cam thu
hieu van » hieu va, thien van, lieu va
nang ma » tang ma, sang ma, nang cao
sach ly » sach y, sach lo, sach ty
van cam » van nam, van lam, van cau
nang xa » nang x, lang xa, mang xa
hai cau » hai chau, hai chu, hoi cau
hai hau » hai chau, dai hau, hai hai
su sach » so sach, vu sach

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: su sach ly ((nang xa) OR (nang ma)) hoi. hieu van cam thuc vat danh ((hai cau) OR (hai hau)) treo~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ly ((nang xa) OR (nang ma)) hoi. hieu van cam thuc vat danh ((hai cau) or (hai hau)) treo~".
• Adding a wildcard symbol may retrieve word variants: su sach ly ((nang xa) OR (nang ma)) hoi. hieu van cam thuc vat danh ((hai cau) or (hai hau)) treo*.