More reference links

Author: ixs

README.md

@@ -16,6 +16,9 @@ Demo Site: https://lto-barcodes.dicp.net
 
  * https://www.ibm.com/support/pages/ibm-lto-ultrium-cartridge-label-specification
  * https://www.ibm.com/support/pages/system/files/support/ssg/ssgdocs.nsf/0/c90cc23311a1bfb985256b840063e5cd/$FILE/19P0034,M10321,R00,001,WORDPRO,PDF.pdf
+ * https://www.ibm.com/docs/en/ts4500-tape-library?topic=labels-bar-code-label-specifications
  * https://am4computers.com/Documents/IBM%20LTO%20Label%20Specification.pdf (Older specs)
  * https://www.tri-optic.com/media/pdf/RevisedTriOpticBrochure.pdf
  * https://www.tri-optic.com/media/pdf/ColorTables.pdf
+ * https://www.sanspot.com/technical/lto-label-reference-guide
+ * https://www.sanspot.com/media/pdfdocuments/lto_label_ref_guide.pdf