     @readBibtexFiles(bibtexFiles)
 
     for citation in @bibtex
-      citation.entryTags.prettyTitle =
-        @prettifyTitle citation.entryTags.title
+      if citation.entryTags and citation.entryTags.title and citation.entryTags.author
+        citation.entryTags.prettyTitle =
+          @prettifyTitle citation.entryTags.title
 
-      citation.entryTags.authors =
-        @cleanAuthors citation.entryTags.author?.split ' and '
-      citation.entryTags.prettyAuthors =
-        @prettifyAuthors citation.entryTags.authors
+        citation.entryTags.authors =
+          @cleanAuthors citation.entryTags.author?.split ' and '
+        citation.entryTags.prettyAuthors =
+          @prettifyAuthors citation.entryTags.authors
 
-      for author in citation.entryTags.authors
-        possibleWords.push {
-          author: @prettifyName(author, yes),
-          key: citation.citationKey,
-          label: "#{citation.entryTags.prettyTitle} \
-            by #{citation.entryTags.prettyAuthors}"
-        }
+        for author in citation.entryTags.authors
+          possibleWords.push {
+            author: @prettifyName(author, yes),
+            key: citation.citationKey,
+            label: "#{citation.entryTags.prettyTitle} \
+              by #{citation.entryTags.prettyAuthors}"
+          }
 
     @possibleWords = possibleWords
 

      bibtex = []

      for file in bibtexFiles
        parser = new bibtexParse(fs.readFileSync(file, 'utf-8'))

        bibtex = bibtex.concat parser.parse()

      @bibtex = bibtex
    catch error

  ###
  wordRegex: /(?:^|\s)@[^\s@]*/
  constructor: ->
    @bibtex = []

    @buildWordList(atom.config.get "autocomplete-bibtex.bibtex")
    atom.config.observe "autocomplete-bibtex.bibtex", (bibtexFiles) =>
      @buildWordList(bibtexFiles)
