http://www.adobe.com/misc/linking.html#pdficon
Adobe PDF file icon
The Adobe PDF file icon is provided solely as an indicator of an active link to a Portable Document Format file with a .pdf filename extension created using an Adobe® Acrobat® product. By downloading or using the icon, you agree to adhere to the following guidelines:
1. You will only display the Adobe PDF file icon on your website and not in any other manner.
2. The Adobe PDF file icon must appear by itself, with a minimum spacing (the height of the icon) between each side of the icon and any other graphic or textual elements on your web page.
3. You may not alter the Adobe PDF file icon in any manner, including size, proportions, colors, elements, and so forth, or animate, morph, or otherwise distort its perspective or appearance.
4. Your use may not be obscene or pornographic, and may not be disparaging, defamatory, or libelous to Adobe, any of its products, or any other person or entity.
5. Your use may not directly or indirectly imply Adobe's sponsorship, affiliation, or endorsement of your product or service.
6. Your use may not infringe any Adobe intellectual property or other rights, may not violate any state or federal laws, and must comply with international IP laws.
7. You may not create a frame or border environment around Adobe content.
8. You may not present false or misleading information about Adobe products or services.
9. Your reference to Adobe, its products, and its website must comply with the general trademark guidelines.
10. These guidelines do not give you permission to use any other Adobe logos, icons, or trademarks. Adobe reserves the right in its sole discretion to terminate or modify your permission to display the Adobe PDF file icon at any time.
If your use meets the above criteria, no further written permission is required, and you may download the image for use in accordance with the guidelines above. Get more information on distributing Adobe Reader® software.
Donc a priori, les seules icônes autorisées sont celles disponible sur la page.
