SEARCH Articles Figures Tables Analysis of Second-Order, Three- and Four-Spin Systems by Inspection Experimental Determination of Reaction Order Simple Systems Frequency response characteristics of first-order systems Frequency response characteristics of second-order systems Further Examples of Simple, First-Order Spin Systems Higher order connections of the accessory olfactory system and reproductive functions Order of a system Order systems Ordered systems Response of higher-order systems Systems of First-Order Ordinary Differential Equations Systems of first-order reactions Systems of higher order The Ground-State Energy to First-Order of Heliumlike Systems