On bitbucket.org the voted solution wouldn't work. Instead, when using headers (with ##), 
it is possible to reference them as anchors by prefixing them 
as #markdown-header-my-header-name, where #markdown-header- is an implicit 
prefix generated by the renderer, and the rest is the lower-cased 
header title with dashes replacing spaces.

Example

    ## My paragraph title

will produce an implicit anchor like this

    #markdown-header-my-paragraph-title
    
The whole URL before each anchor reference is optional, i.e.

    [Some text](#markdown-header-my-paragraph-title)

is equivalent of

    [Some text](https://bitbucket.org/some_project/some_page#markdown-header-my-paragraph-title) 

provided that they are in the same page.