000			00316 a2200145 4500
020			_a0216902436
041			_aEn
082			_a570 _bEXC
245			_aExchanging materials
260			_aLondon _bBlackie & Son Limited
300			_c25 cm. _a48 p .
650			_aNatural sciences
650			_aBiology
942			_cSR
999			_c19054 _d20601