Ohlman published a variety of papers on Permuterm and other Information Science and Technology and communication topics, which are now at the Charles Babbage Institute at The University of Minnesota.
In 1958 Ohlman submitted a paper titled "Subject-word letter frequencies with applications to superimposed coding" to the International Conference on Scientific Information (ICSI) in Washington, DC.
At the conference, Ohlman saw the "perfect way to demonstrate the speed and automation features of permutation indexing to information science and technology colleagues."
Luhn's system used punched cards only for input, converted the data to punched-paper tape, and used a computer to produce the final index.
He worked for a variety of companies, including: He was also a consultant in information science and technology for the World Health Organization in Geneva, Switzerland.