<athe literal text <a (case sensitive) \s+any whitespace character, repeated at least once
.*?any character (except for line terminators), repeated any number of times
href=the literal text href= (case sensitive) ?matches at most one character from the set below:
'the literal ' (3910 / 478 / 2716)
"the literal " (3410 / 428 / 2216)
\S*any non-whitespace character, repeated any number of times
\2the text saved by group 2