Perhaps you should try some spelling variations:
nam thuoc » nam thu, nha thuoc, cay thuoc
toc sach » hoc sach, doc sach, thuoc sach
hieu van » hieu va, thien van, lieu va
nam thuc » am thuc, nam thu, nam tu
dan vanh » dan canh, dan hanh, dang hanh
vanh dai » van dai, vanh tai, lanh dao
ky lang » ky nang, ky dang, ky tang
lang xa » lang ha, dang xay, lang van
cua tre » cua te, cuu tre, cua triet

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

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) or (toc sach)) ky lang xa hoi. hieu van ((nam thuc) OR (nam thuoc)) dan vanh dai cua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((te sach) OR (toc sach)) ky lang xa hoi. hieu van ((nam thuc) OR (nam thuoc)) dan vanh dai cua tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) or (toc sach)) ky lang xa hoi. hieu van ((nam thuc) OR (nam thuoc)) dan vanh dai cua tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) or (toc sach)) ky lang xa hoi. hieu van ((nam thuc) OR (nam thuoc)) dan vanh dai cua tre*.