Average Co-Inventor Count = 1.33
ph-index = 2
The patent ph-index is calculated by counting the number of publications for which an author has been cited by other authors at least that same number of times.
Company Filing History:
1. National Blank Book Company, Inc. (2 from 8 patents)
2 patents:
1. 4181381 - Filing device
2. 4119200 - Tape cassette holder