Perhaps you should try some spelling variations:
doc sach » hoc sach, toc sach, nuoc sach
sach ky » sac ky, sach y, sach ty
ky dang » ky nang, ky danh
dang xa » dang xay, lang xa, dang ha
hieu va » lieu va, hieu qua
thuc va » thuc dan, thuc day
buu tre » cuu tre
va nam » van nam, ha nam, va nay
da tai » dai tai, dat tai, da thai

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

• Performing a fuzzy search may retrieve terms with similar spellings: doc sach ky dang xa hoi. hieu va nam ((thuc va) or (thuc vat)) da tai buu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: doc sach ky dang xa hoi. hieu va nam ((thuc va) OR (thuc vat)) da tai buu tre.
• Adding a wildcard symbol may retrieve word variants: doc sach ky dang xa hoi. hieu va nam ((thuc va) or (thuc vat)) da tai buu tre*.