731 wienold2018 pdf cache all wpfb_file_category citations 1554750587 b9698b3ef318f4eecec1d73b49d13cc4 59915d822e89d9a36813474a509705e3f3b5e0e362fcbe792905b7b856cabd39 doppler free spectroscopy with a terahertz quantum cascade laser 2018 02 14 13 09 47 wienold et al 0 66 249 64 38 2020 01 03 11 22 30 release pdf application num_pages analyze pdf_pages pdf_2text timings