Adding reference citations

The blockquote element can have a cite attribute, and the content from this attribute
can be displayed by using the following CSS rule. Note, however, that at the time of writing,
this doesn’t work in Internet Explorer.
blockquote[cite]:after {
display : block;
margin : 0 0 5px;
padding : 0 0 2px 0;
font-weight : bold;
font-size : 90%;
content : "[source: "" " attr(cite)"]";
}