Various minor adjustments to snippets

UltiSnips/bib.snippets

@@ -18,9 +18,9 @@ endsnippet
 
 snippet article "Add article reference" b
 @article{${1:ref_name},
-	title={${2:Titel}},
-	author={${3:Autor}},
-	journal={${4:Journal}},`!p
+	title	= {${2:Titel}},
+	author	= {${3:Autor}},
+	journal	= {${4:Journal}},`!p
 if t[5] != "":
 	snip.rv = "\n\tvolume\t= {"
 else:
@@ -45,8 +45,9 @@ if t[7] != "":
 	snip.rv = "},"
 else:
 	snip.rv = ""`
-	year={${8:2023}},
-	publisher={${9:Verlag}}
+	year	= {${8:2023}},
+	doi		= {${9:DOI_NUM}}
+	publisher = {${10:Verlag}}
 }
 $0
 endsnippet