Perhaps you should try some spelling variations:
toc sach » hoc sach, doc sach, thuoc sach
nam thuc » nam thuoc, am thuc, nam thu
vai cuu » vai cua
sach ky » sac ky, sach y, sach ty
cuu tre » cua tre, cau tren, cau treo
hieu ca » hieu cac, hieu cua, hieu va
ky lang » ky nang, ky dang, ky tang
ha hoi » hoa hoi, ha noi, va hoi
va dan » va dao, va dau, va dap
ca dan » cac dan, ca dao
ca nam » cua nam, cai nam, ha nam

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