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

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 xa hoi. hieu ca nam thuc ((va dan) or (ca dan)) vai cau tren~.
• If you are trying to use Boolean operators, they must be ALL CAPS: toc sach ky lang xa hoi. hieu ca nam thuc ((va dan) OR (ca dan)) vai cau tren.
• Adding a wildcard symbol may retrieve word variants: toc sach ky lang xa hoi. hieu ca nam thuc ((va dan) or (ca dan)) vai cau tren*.