Perhaps you should try some spelling variations:
sach ty » sach y, sach tu, sach thu
dang xa » dang xay, lang xa, dang ha
vat dan » va dan, van dan, vat ran
cua tre » cua te, cuu tre, cua triet
sac ky » cac ky, sai ky
va nam » van nam, va nay
dan va » doan va, dan ca, ban va
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: toc ((sach ty) or (sac ky)) dang xa hoi. hieu ((va nam) or (ha nam)) thuc vat dan va cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc ((sach ty) OR (sac ky)) dang xa hoi. hieu ((va nam) OR (ha nam)) thuc vat dan va cua tre.
• Adding a wildcard symbol may retrieve word variants: toc ((sach ty) or (sac ky)) dang xa hoi. hieu ((va nam) or (ha nam)) thuc vat dan va cua tre*.