00290nam a2200109Ia 450000500170000000800410001708200140005810000160007224500380008826000460012630000080017220260225051015.0260224s9999||||xx |||||||||||||| ||und||  a574.8 QUI  aA. Quispel  4aThe biology of nitrogen fixation   aOxford: North-Holland Pub. Company c1974  a769