Perhaps you should try some spelling variations:
dao thanh » ban thanh, tro thanh, de thanh
da thanh » dat thanh, dam thanh, dan thanh
hieu van » hieu va, thien van, lieu va
cam thuc » nam thuc, cam thu, can thuc
so sach » so sanh, bo sach, co sach
cua tre » cua te, cuu tre, cua triet
sach ty » sach y, sach tu, sach thu
nang xa » nang x, lang xa, nang ma
ty nang » ky nang, ty xang, ty hang
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: so sach ty nang xa hoi. hieu van ((cam thuc) or (am thuc)) ((da thanh) OR (dao thanh)) va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: so sach ty nang xa hoi. hieu van ((cam thuc) OR (am thuc)) ((da thanh) OR (dao thanh)) va cua tre*.
• The words AND, OR and NOT may confuse the search; try adding quotes: "so sach ty nang xa hoi. hieu van ((cam thuc) or (am thuc)) ((da thanh) OR (dao thanh)) va cua tre*".