Index base call numbers for search and "forward" / "backward" navigation https://github.com/psu-libraries/psulib_blacklight/wiki/Browse-Items-by-Library-of-Congress-Call-Number#indexing SUDOC: - HE 20.427:B 87/4/2008 - HE 20.427:C 76/2/KIT. - HE 20.427:H 33 - HE 20.427:H 75/PACK. - HE 20.427:IL 6/KIT - HE 20.427:IN 7 ASIS: - Microfilm D302 - Microfilm D323 - Microfilm F401 - Microfilm F402 - Microfilm F402a You can also refer to the current CAT to do call number search for each type or use the "Browse nearby on shelf" from an item record.