Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
nam thuc » nam thuoc, am thuc, nam thu
ky tang » ky nang, ky dang, kho tang
tang xa » trang xa, tang ma, lang xa
hieu va » lieu va, hieu qua
thuc va » thuc vat, thuc dan, thuc day
dau tai » dai tai, dat tai, da tai
buu tre » cuu tre
va nam » van nam, ha nam, va nay
va dau » va dao

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) OR (doc sach)) ky tang xa hoi. hieu va nam thuc va dau tai buu tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) OR (doc sach)) ky tang xa hoi. hieu va nam thuc va dau tai buu tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) OR (doc sach)) ky tang xa hoi. hieu va nam thuc va dau tai buu tre*.