Phosphorus-bearing molecules in solar-type star-forming regions: first PO detection - Lefloch, Bertrand; Vastel, C; Viti, S; Jimenez-Serra, I; Codella, C; Podio, I; Ceccarelli, C; Mendonza, E; Lépine, Jacques Raymond Daniel; Bachiller, R (Monthly Notices of the Royal Astronomical Society, 2016)