Perhaps you should try some spelling variations:
nang doc » nang luc
sach ty » sach y, sach tu, sach thu
kem cua » em cua, keo cua, diem cua
va hanh » van hanh, va thanh, va danh
thuc va » thuc vat, thuc dan, thuc day
cua tre » cua te, cuu tre, cua triet
doc hoi » duoc hoi, hoc hoi, doc hai
ve cac » va cac, vien cac
sac ky » cac ky, sai ky
ve cam » ve cham, va cam, ve cai

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 ty) or (sac ky)) nang doc hoi. hieu ((ve cam) or (ve cac)) thuc va hanh kem cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach ty) OR (sac ky)) nang doc hoi. hieu ((ve cam) OR (ve cac)) thuc va hanh kem cua tre.
• Adding a wildcard symbol may retrieve word variants: tu ((sach ty) or (sac ky)) nang doc hoi. hieu ((ve cam) or (ve cac)) thuc va hanh kem cua tre*.