support variables in cite tag

features/citation.feature

@@ -215,3 +215,30 @@ Feature: Citations
     And the "_site/scholar.html" file should exist
     And I should see "\[1\], \[2\]" in "_site/scholar.html"
 
+  @tags @cite @variables
+  Scenario: A Simple Citation using liquid variables
+    Given I have a scholar configuration with:
+      | key          | value             |
+      | source       | ./_bibliography   |
+      | bibliography | my_references     |
+    And I have a "_bibliography" directory
+    And I have a file "_bibliography/my_references.bib":
+      """
+      @book{ruby,
+        title     = {The Ruby Programming Language},
+        author    = {Flanagan, David and Matsumoto, Yukihiro},
+        year      = {2008},
+        publisher = {O'Reilly Media}
+      }
+      """
+    And I have a page "scholar.html":
+      """
+      ---
+      ---
+      {% assign myVariable = 'ruby' %}
+      {% cite myVariable %}
+      """
+    When I run jekyll
+    Then the _site directory should exist
+    And the "_site/scholar.html" file should exist
+    And I should see "Flanagan" in "_site/scholar.html"

lib/jekyll/scholar/utilities.rb

@@ -327,6 +327,9 @@ module Jekyll
 
       def cite(keys)
         items = keys.map do |key|
+          # dereference variables in current scope
+          key = context.scopes.last[key] || key
+
           if bibliography.key?(key)
             entry = bibliography[key]
             entry = entry.convert(*bibtex_filters) unless bibtex_filters.empty?