diff --git a/opt4j-core/src/main/java/org/opt4j/core/config/annotations/Citation.java b/opt4j-core/src/main/java/org/opt4j/core/config/annotations/Citation.java
index 0ff185d0..1ad2f7f1 100644
--- a/opt4j-core/src/main/java/org/opt4j/core/config/annotations/Citation.java
+++ b/opt4j-core/src/main/java/org/opt4j/core/config/annotations/Citation.java
@@ -47,24 +47,24 @@ public Month toMonth() {
 				return Month.JANUARY;
 			case FEBRUARY:
 				return Month.FEBRUARY;
-			case APRIL:
-				return Month.APRIL;
-			case AUGUST:
-				return Month.AUGUST;
-			case JULY:
-				return Month.JULY;
-			case JUNE:
-				return Month.JUNE;
 			case MARCH:
 				return Month.MARCH;
+			case APRIL:
+				return Month.APRIL;
 			case MAY:
 				return Month.MAY;
-			case NOVEMBER:
-				return Month.NOVEMBER;
-			case OCTOBER:
-				return Month.OCTOBER;
+			case JUNE:
+				return Month.JUNE;
+			case JULY:
+				return Month.JULY;
+			case AUGUST:
+				return Month.AUGUST;
 			case SEPTEMBER:
 				return Month.SEPTEMBER;
+			case OCTOBER:
+				return Month.OCTOBER;
+			case NOVEMBER:
+				return Month.NOVEMBER;
 			case DECEMBER:
 				return Month.DECEMBER;
 			default:
diff --git a/opt4j-core/src/test/java/org/opt4j/core/config/annotations/CitationTest.java b/opt4j-core/src/test/java/org/opt4j/core/config/annotations/CitationTest.java
new file mode 100644
index 00000000..93e520eb
--- /dev/null
+++ b/opt4j-core/src/test/java/org/opt4j/core/config/annotations/CitationTest.java
@@ -0,0 +1,36 @@
+package org.opt4j.core.config.annotations;
+
+import java.time.DateTimeException;
+import java.time.Month;
+
+import org.junit.Assert;
+import org.junit.Test;
+import org.opt4j.core.config.annotations.Citation.PublicationMonth;
+
+public class CitationTest {
+	@Test
+	public void toMonth() {
+		Assert.assertEquals(Month.JANUARY, PublicationMonth.JANUARY.toMonth());
+		Assert.assertEquals(Month.FEBRUARY, PublicationMonth.FEBRUARY.toMonth());
+		Assert.assertEquals(Month.MARCH, PublicationMonth.MARCH.toMonth());
+		Assert.assertEquals(Month.APRIL, PublicationMonth.APRIL.toMonth());
+		Assert.assertEquals(Month.MAY, PublicationMonth.MAY.toMonth());
+		Assert.assertEquals(Month.JUNE, PublicationMonth.JUNE.toMonth());
+		Assert.assertEquals(Month.JULY, PublicationMonth.JULY.toMonth());
+		Assert.assertEquals(Month.AUGUST, PublicationMonth.AUGUST.toMonth());
+		Assert.assertEquals(Month.SEPTEMBER, PublicationMonth.SEPTEMBER.toMonth());
+		Assert.assertEquals(Month.OCTOBER, PublicationMonth.OCTOBER.toMonth());
+		Assert.assertEquals(Month.NOVEMBER, PublicationMonth.NOVEMBER.toMonth());
+		Assert.assertEquals(Month.DECEMBER, PublicationMonth.DECEMBER.toMonth());
+	}
+
+	@Test(expected = DateTimeException.class)
+	public void toMonthUnkown() {
+		PublicationMonth.UNKNOWN.toMonth();
+	}
+
+	@Test
+	public void valueOf() {
+		Assert.assertEquals(PublicationMonth.JANUARY, PublicationMonth.valueOf("JANUARY"));
+	}
+}