Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
tu nang » tru nang, tu nong, tu nano
hieu va » lieu va, hieu qua
co thuc » do thuc, co thua, mo thuc
thuc va » thuc vat, thuc dan, thuc day
va hanh » van hanh, va thanh, va danh
hanh va » hang va, hanh vi
cuu tre » cua tre, cau tren, cau treo
va cuu » va cau, va chu, va huu
x hoi » xa hoi, o hoi, x ho
va co » vo co

You may be able to get more results by adjusting your search query.

• Performing a fuzzy search may retrieve terms with similar spellings: ((te sach) OR (toc sach)) tu nang x hoi. hieu va co thuc va hanh va cuu tre~.
• The words AND, OR and NOT may confuse the search; try adding quotes: "((te sach) OR (toc sach)) tu nang x hoi. hieu va co thuc va hanh va cuu tre".
• Adding a wildcard symbol may retrieve word variants: ((te sach) OR (toc sach)) tu nang x hoi. hieu va co thuc va hanh va cuu tre*.