Perhaps you should try some spelling variations:
thuoc sach » hoc sach, nuoc sach, thuat sach
toc sach » hoc sach, doc sach, nuoc sach
thuc dan » thuc hanh, thuc vat
hieu va » lieu va, hieu qua
lang ha » long ha
ky lang » ky nang, ky dang, ky tang
cuu tre » cua tre, cau tren, cau treo
ha hoi » hoa hoi, ha noi, xa hoi
dan va » doan va, dan ca, ban va
va cuu » va cau, va chu, va huu
va am » va lam, va cam

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