From 6060113df56b871bb5014a8a961974895e52158f Mon Sep 17 00:00:00 2001
From: Axel Nieder-Vahrenholz <nieder-vahrenholz@hebis.uni-frankfurt.de>
Date: Mon, 6 Apr 2020 09:58:51 +0000
Subject: [PATCH] feat: Update src/things/book.ts - made ISBN optional

---
 src/things/book.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/src/things/book.ts b/src/things/book.ts
index 7d2505ab..86434db9 100644
--- a/src/things/book.ts
+++ b/src/things/book.ts
@@ -42,7 +42,7 @@ export interface SCBookWithoutReferences
    * @filterable
    * @keyword
    */
-  isbn: string;
+  isbn?: string;
 
   /**
    * Number of pages of a book