Hi Nad,
The reason why the parser is choking on these posts is because the html anchor syntax that you are using isn't supported (at least directly).

But the Markdown syntax for links works fine.

This text:

Here is a link about the [Montavid research group](http://www.mathnet.ru/php/organisation.phtml?option_lang=eng&orgid=6220)

Produces this result:

Here is a link about the [Montavid research group](http://www.mathnet.ru/php/organisation.phtml?option_lang=eng&orgid=6220)