Perhaps you should try some spelling variations:
sach kha » sach nha, sach ha, sach tham
hang vai » hang tai, hang hai, hang vi
cam thuc » am thuc, nam thuc, cam thu
tu sach » thu sach, su sach, te sach
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
hieu ve » hieu va, hieu van
nang xa » lang xa, nang ma, mang xa
ve cam » ve cham, ve cac, va cam

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

• Performing a fuzzy search may retrieve terms with similar spellings: tu sach kha ((nang xa) OR (nang x)) hoi. hieu ve cam thuc va ((hang vai) or (hang va)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu sach kha ((nang xa) OR (nang x)) hoi. hieu ve cam thuc va ((hang vai) OR (hang va)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu sach kha ((nang xa) OR (nang x)) hoi. hieu ve cam thuc va ((hang vai) or (hang va)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu sach kha ((nang xa) OR (nang x)) hoi. hieu ve cam thuc va ((hang vai) or (hang va)) cua tre*.