I don't see any issues with providing links to stuff on the internet.
Afterall, the web page owner put the page out there for folks to look
at. I have links in my clue pages leading to city and state run sites
that I included without a thought. When I'm linking to another
letterboxer's page I usually let them know as a courtesy.

--- In letterbox-usa@y..., stampinpam@a... wrote:
> I'm trying to write clues for the first letterbox I have planted.
What is
> the protocol for using hyperlinks in your clues? I have found two
sites that
> contain wonderful ecological and historical information on the area
where the
> letterbox is located.
>
> Is it acceptable to put the URLs in my clues? Should you obtain
permission
> from those websites first? Your input is appreciated. Thanks in
advance,
> StampinPam