The sound approach to birding : a guide to understanding bird sound / Mark Constantine & The Sound Approach ; [photogr.: Arnoud B. van den Berg ... et al. ; text ed.: Arnoud B. van den Berg ... et al.]Catching the bug : a Sound Approach guide to the birds of Poole Harbour / [text:] Mark Constantine, Nick Hopper & The Sound Approach ; [maps: Cecilia Bosman ; photogr.: Nick Hopper ... et al. ; text ed.: Magnus Robb ... et al.]