He has built a cutting-edge library of digital communication and books on science and technology in the city for everyone to access.

Debasish Som, whose passion is knowledge and who gave up his job in the IAS to work in the private sector so that he could devote more time to study, has about 6,000 books in his library housed in four rooms on the first floor of his residence at Ballygunge. The books, collected over 30 years, cover a range of subjects, including digital communication, physics, mathematics, economics and management.

Besides, he has 156GB worth of soft copy of books and notes on mathematics and digital communication. 'My collection of digital communication is probably the best on the subject in India,' Som claims.

Anyone can visit the library. He or she has to get an appointment on phone (9830068606) before visiting.

Problems in procuring US editions of books for higher studies in Calcutta and curtailment of library grants to the IITs prompted Som to throw open his personal library, worth over Rs 2 crore, to students and researchers.

Som, 54, was commissioner, Calcutta Municipal Corporation. Now he is CEO, Bengal Sriram Hitech City. He studied electronic engineering at IIT Kharagpur. He resigned from the IAS in 2007 and turned the first floor of his home into his library, which is also on display on his LinkedIn profile.

The library includes the first set of books Som treasured: The Feynman Lectures on Physics he had procured, when he was 13, after taking a transfer from the Hindu School to South Point School in 1974. Other books he likes to mention include Lectures on The Calculus of Variations (1904) by Oskar Bolza, Gakhov's Boundary Value Problem, Lanczos's Discourse on Fourier Series, Functional Analysis of Brown & Page, Modulation Theory by Black, Panter's Modulation Noise, Functional Analysis of Lusternik Sobolev, four volumes of Reed Simon's Functional Analysis and five volumes of Smirnov's Course on Higher Mathematics.

Som likes to remember his physics teacher at South Point, Anjan Baran Dasgupta, saying: 'Physics is 80% English and 10% science.'

Som is worried about the problems facing higher studies in electronics and digital communication, particularly in Calcutta. First, books are very costly and most teachers do not remain abreast of the latest research, he said. Second, procurement of books is a problem. Unlike in Hyderabad, there is no showroom of McGraw Hill or Prentice Hall in Calcutta. Hence US editions are not easily available. There is no way of buying books in Indian currency. Even second-hand books are hard to get. 'I had been in search of a copy of Digital Coding of Waveforms by Jayant & Noll since 1982 and after 21 years in 2013 I found it at Amazon.com. But they refused to send it to India. My friend Rahul Saraf of Forum was then in the US. I bought the book through him,' said Som.

'The library is really a treasure trove of rare collections. I found some books here I could not find at IIT Kharagpur. If Som opens it to students of MSc and higher levels it will really be an El Dorado to them because there is hardly any place in Calcutta and Bengal where so many books on communication, optics and mathematics are found under a single roof,' said Pradip Dutta, vice-president and managing director of Synopsys, India, over telephone from Bangalore. 'Whenever I come to Calcutta, I visit Som's library,' he said.

Som believes that in his old age mathematics will keep him agile. His greatest satisfaction is that his daughter Debasmita, a telecom engineer, has promised to take over the charge of the library from him.