Search for radiative pumping lines of OH masers - I. The 34.6 μm absorption line towards 1612 MHz OH maser sourcesJ. H. He, R. Szczerba, P. S. Chen and A. M. SobolevA&A, 434 1 (2005) 201-211DOI: https://doi.org/10.1051/0004-6361:20040569
