Improvement by sorting and thresholding in PCA based nearest neighbor search. - Hidetomo Ichihashi; Toshiro Ogita; Katsuhiro Honda; Akira Notsu (FUZZ-IEEE, 2012)

PCA-Tree NNS with two approximation methods and annulus bound method. - Hidetomo Ichihashi; Toshiro Ogita; Akira Notsu; Katsuhiro Honda (SCIS&ISIS, 2012)

Improvement of PCA-Based Approximate Nearest Neighbor Search Using Distance Statistics. - Toshiro Ogita; Hidetomo Ichihashi; Akira Notsu; Katsuhiro Honda (J. Adv. Comput. Intell. Intell. Informatics, 2014)