Perhaps you should try some spelling variations:
toc sach » hoc sach, thuoc sach, nuoc sach
doc sach » hoc sach, nuoc sach, dac sac
xanh di » vanh dai, xanh tai
danh di » danh du, danh dien, danh gia
cam luc » cam xuc, cau luc
hieu va » lieu va, hieu qua
cuu tre » cua tre, cau tren, cau treo
nang o » nang co, nang ho, nang ro
luc va » duc va, tuc va, loc va
v nang » va nang, vu nang, van nang
va cam » va cham, va cac, va cao
o hoi » co hoi, o hoc, o hai

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)) v nang o hoi. hieu va cam luc va ((danh di) OR (xanh di)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: ((toc sach) OR (doc sach)) v nang o hoi. hieu va cam luc va ((danh di) OR (xanh di)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((toc sach) or (doc sach)) v nang o hoi. hieu va cam luc va ((danh di) OR (xanh di)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((toc sach) or (doc sach)) v nang o hoi. hieu va cam luc va ((danh di) OR (xanh di)) cuu tre*.