Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
thuc dan » thuc hanh, hoc dan, thuc vat
sach ky » sac ky, sach y, sach ty
thuc va » thuc vat, thuc day
cuu tre » cua tre, cau tren, cau treo
hieu va » hieu qua
long xa » song xa, long ha, lang xa
ky long » ky cong, sy long, ky trong
dan va » doan va, dan ca, ban va
va cuu » va cau, va chu, va huu

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 long xa hoi. ((hieu va) or (lieu va)) nam ((thuc va) OR (thuc dan)) dan va cuu tre~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky long xa hoi. ((hieu va) OR (lieu va)) nam ((thuc va) OR (thuc dan)) dan va cuu tre.
• The words AND, OR and NOT may confuse the search; try adding quotes: "toc sach ky long xa hoi. ((hieu va) or (lieu va)) nam ((thuc va) OR (thuc dan)) dan va cuu tre".
• Adding a wildcard symbol may retrieve word variants: toc sach ky long xa hoi. ((hieu va) or (lieu va)) nam ((thuc va) OR (thuc dan)) dan va cuu tre*.