Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
sach han » sach tham, sach danh, sach nang
dau tren » dau tien, dat tren, dau tieng
han nang » phan nang, van nang, ban nang
hieu va » lieu va, hieu qua
cam luc » cam xuc, cau luc
va danh » va dinh, va dan, va hanh
danh di » danh du, xanh di, danh dien
cuu tre » cua tre, cau tren, cau treo
co hai » co dai, co hoi, so hai
luc va » duc va, tuc va, loc va
va cam » va cham, va cac, va cao
o hai » so hai, o lai, _ 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 han nang ((o hai) OR (co hai)). hieu va cam luc va danh di ((cuu tre) or (dau tren))~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach han nang ((o hai) OR (co hai)). hieu va cam luc va danh di ((cuu tre) OR (dau tren)).
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach han nang ((o hai) OR (co hai)). hieu va cam luc va danh di ((cuu tre) or (dau tren))".
• Adding a wildcard symbol may retrieve word variants: toc sach han nang ((o hai) OR (co hai)). hieu va cam luc va danh di ((cuu tre) or (dau tren))*.