How do I add Google Scholar meta tags to a custom content type? I use drupal 7 and I have custom content type named "Journal"
I want add Google Scholar meta tags to "Journal" nodes.
Like this:

&lt;meta name="citation_journal_title" content="Journal Name"&gt;
&lt;meta name="citation_authors" content="Last Name1, First Name1; Last Name2, First Name2"&gt;
&lt;meta name="citation_title" content="Article Title"&gt;
&lt;meta name="citation_date" content="01/01/2007"&gt;
&lt;meta name="citation_volume" content="10"&gt;
&lt;meta name="citation_issue" content="1"&gt;
&lt;meta name="citation_firstpage" content="1"&gt;
&lt;meta name="citation_lastpage" content="15"&gt;
&lt;meta name="citation_doi" content="10.1074/jbc.M309524200"&gt;
&lt;meta name="citation_pdf_url" content="http://www.publishername.org/10/1/1.pdf"&gt;
&lt;meta name="citation_abstract_html_url" content="http://www.publishername.org/cgi/content/abstract/10/1/1"&gt;
&lt;meta name="citation_fulltext_html_url" content="http://www.publishername.org/cgi/content/full/10/1/1"&gt;  
&lt;meta name="dc.Contributor" content="Last Name1, First Name1"&gt;
&lt;meta name="dc.Contributor" content="Last Name2, First Name2"&gt;
&lt;meta name="dc.Title" content="Article Title"&gt;
&lt;meta name="dc.Date" content="01/01/2007"&gt;
&lt;meta name="citation_publisher" content="Publisher Name"&gt;
&lt;meta name="robots" content="noarchive"&gt;


I tried the Metatag and Custom Meta modules. With the Metatag module, I can't add custom meta tags; with the Custom Meta module, I can't add custom meta tags to a content type.

How can I achieve this?
There is a module that allows adding Google Scholar meta tags: https://www.drupal.org/project/metatag_google_scholar . However, it is only available for Drupal 8.

I post this answer anyway, in case it might be useful (as an inspiration for a backport, for instance).