We characterize sheets of white paper using three bidirectional reflectance distribution function (BRDF) model parameters estimated from the BRDF in the specular reflection plane. The radiance factors of eight types of paper sheets having a wide range of material characteristics were measured for 284 geometries in the specular reflection plane. They were approximated within an average error of 4.5% using a linear combination of Torrance-Sparrow and Lambert's BRDF models. The proposed model well approximated the BRDF of samples in the specular plane. Based on the estimated BRDF model parameters, the eight measured paper sheets could be broadly classified into glossy papers and rough papers. The two glossy papers were distinguishable from each other, while the six rough papers could be classified into three groups using the BRDF model parameters. The proposed method is considered to be effective for characterizing a wide range of white paper ranging from glossy to matte paper.