Arjo Segers Arnold W. Heemink Martin Verlaan Maarten van Loon A modified -filter for assimilating data in atmospheric chemistry models. 663-671 2000 15 Environmental Modelling and Software 6-7 db/journals/envsoft/envsoft15.html#SegersHVL00 http://dx.doi.org/10.1016/S1364-8152(00)00051-7