Within-subject variation in BOLD-fMRI signal changes across repeated measurements: Quantification and implications for sample size. - Bram B. Zandbelt; Thomas E. Gladwin; Mathijs Raemaekers; Mariët van Buuren; Sebastiaan F. W. Neggers; René S. Kahn; Nick F. Ramsey; Matthijs Vink (NeuroImage, 2008)