Comments on: semi-rigid urethane even better? http://metabiosis.kuri.mu/2007/12/15/semi-rigit-urethane-even-better/ Dependence of one organism on another for the preparation of an environment in which it can live. Mon, 21 Feb 2011 00:35:30 +0000 hourly 1 https://wordpress.org/?v=4.4.2