His notes, however, were not published until nine years later as his fourth book Fourier integral and questions connected with it in 1944 (reprinted in 1967).
Ang kanyang mga tala, gayunpaman, ay hindi nai-publish na hanggang siyam na taon mamaya bilang ng kanyang ika-apat na libro Fourier mahalaga at mga katanungan na konektado sa mga ito sa 1944 (reprinted in 1967).