Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
tang mai » tang ma, tang tai, lang mai
hieu van » hieu va, thien van, lieu va
chua tre » chua tri, cua tre, chua trieu
mai hoi » mai khoi, dai hoi, lai hoi
van cam » van nam, van lam, van cau
dinh va » dinh van, dinh ve, tinh va
va chua » vua chua, ca chua, va chu
y tang » ky tang, 6 tang, 7 tang
xuc va » tuc va, luc va, xac va

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)) y tang mai hoi. hieu van cam ((xuc va) or (duc va)) dinh va chua tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) y tang mai hoi. hieu van cam ((xuc va) OR (duc va)) dinh va chua tre.
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) y tang mai hoi. hieu van cam ((xuc va) or (duc va)) dinh va chua tre*.