Perhaps you should try some spelling variations:
dat thanh » dao thanh, dat khanh, dang thanh
hieu van » hieu va, thien van, lieu va
thanh va » thanh van, hanh va, thanh ha
cam thuc » nam thuc, cam thu, can thuc
sach ty » sach y, sach tu, sach thu
su sach » so sach, vu sach
nang ma » tang ma, sang ma, nang cao
nang xa » nang x, lang xa, mang xa
cua tre » cua te, cuu tre, cua triet
va cua » va chua, via cua, ca cua

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

• Performing a fuzzy search may retrieve terms with similar spellings: su sach ty ((nang xa) OR (nang ma)) hoi. hieu van ((cam thuc) or (am thuc)) dat thanh va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: su sach ty ((nang xa) OR (nang ma)) hoi. hieu van ((cam thuc) OR (am thuc)) dat thanh va cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "su sach ty ((nang xa) OR (nang ma)) hoi. hieu van ((cam thuc) or (am thuc)) dat thanh va cua tre*".