Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
cac nuoc » cap nuoc, hoc nuoc, dat nuoc
sach ky » sac ky, sach y, sach ty
ky sang » ky nang, ky dang, ky tang
dai hoi » dai hoc, dai hai, dai moi
danh vi » dinh vi, danh di, danh va
cuu tre » cua tre, cau tren, cau treo
ma hoi » mai hoi, xa hoi, ma hoa

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 ky sang ((ma hoi) or (dai hoi)). lieu va cac nuoc va ((danh vi) OR (hanh vi)) cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky sang ((ma hoi) OR (dai hoi)). lieu va cac nuoc va ((danh vi) OR (hanh vi)) cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky sang ((ma hoi) or (dai hoi)). lieu va cac nuoc va ((danh vi) OR (hanh vi)) cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky sang ((ma hoi) or (dai hoi)). lieu va cac nuoc va ((danh vi) OR (hanh vi)) cuu tre*.