Correctly define pages in bibliography

bibliography.bib

@@ -6,7 +6,7 @@
  publisher = "Aufbau Taschenbuch Verlag",
  translator = "Gesine Schröder",
  year = 2014,
- pages = 237,
+ pagetotal = 237,
  isbn = 9783746626741,
 }
 @book{wyllie-warlord-renegade,
@@ -16,7 +16,7 @@
  location = "Cheltenham",
  publisher = "Sutton Publishing",
  year = 2006,
- pages = 248,
+ pagetotal = 248,
  isbn = 0750940255,
 }
 @book{freitag-ritter-reichsmarschall-revoluzzer,
@@ -26,7 +26,7 @@
  location = "Berlin",
  publisher = "edition Friedenauer Brücke",
  year = 2015,
- pages = 87,
+ pagetotal = 87,
  isbn = 9783981613025,
 }
 @article{spörlgl,
@@ -35,7 +35,7 @@
  journal = "DER SPIEGEL",
  number = 10,
  year = 2013,
- pages = 150--153,
+ pages = "150--153",
  url = "https://magazin.spiegel.de/EpubDelivery/spiegel/pdf/91346615",
 }
 @inbook{nara-report,