The article linked above is by a young UK Blogger, Zoella, discussing her experiences with panic attacks & anxiety. She's also made an amazing video blog about her experiences below
A page from Youth Beyond Blue about what anxiety is as well as providing links with more detailed information about the differing kinds of anxiety and how to deal with it.
Orygen Youth Health - Anxiety
Orygen Youth Health is a Melbourne based organisation which aims to assist young people with mental health concerns. This fact sheet has some useful info about what it's like having anxiety, the different types of anxiety, and how to help someone you know with anxiety.
Orygen Youth Health - Anxiety Medication
Another fact sheet from Orygen Youth Health in Melbourne. This booklet explains the different types of medication commonly prescribed by a doctor to help with anxiety.
Kids Help Line - Anxiety
This Kids Helpline page discusses when anxiety is normal or not normal. It describes the symptoms, different anxiety types, and information on how to manage anxiety.
Worry Wise Kids
Worry Wise Kids was launched in 2004 by the Children's Center for OCD and Anxiety in USA because of the urgent need to address the growing needs of young people to be equipped to cope with and overcome the stress, worry and anxieties in their life.
National Institute of Mental Health - Anxiety
The Nation Institute of Mental Health in USA provides an easy-to-read booklet on generalized anxiety disorder that explains what it is, when it starts, how long it lasts, and how to get help.