Perhaps you should try some spelling variations:
sach kem » hanh kem
cam cua » ca cua, nam cua, cau cua
hieu va » lieu va, hieu qua
lang xa » lang ha, dang xay, lang van
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
va cam » va cham, va cac, va cao
dan vi » doan vi, dan va, gan vi

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 kem) or (sac ky)) lang xa hoi. hieu va cam cua ban ((dan vi) OR (don vi)) cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: tu ((sach kem) OR (sac ky)) lang xa hoi. hieu va cam cua ban ((dan vi) OR (don vi)) cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "tu ((sach kem) or (sac ky)) lang xa hoi. hieu va cam cua ban ((dan vi) OR (don vi)) cua tre".
• Adding a wildcard symbol may retrieve word variants: tu ((sach kem) or (sac ky)) lang xa hoi. hieu va cam cua ban ((dan vi) OR (don vi)) cua tre*.