add publication class template

input/pub.py

@@ -13,8 +13,8 @@ class Publication:
         self.subjects = subjects
         self.num_citations = num_citations
         self.num_references = num_references
-	self._citations = []
-	self._references = []
+    	self._citations = []
+    	self._references = []
 
 class Citation:
     def __init__(self, title, journal, contributors, doi_url):