Wolff, J. K., Brose, A., Lövdén, M., Tesch-Römer, C., Lindenberger, U., & Schmiedek, F. (2012). Health is health is health? Age differences in intraindividual variability and in within-person versus between-person factor structures of self-reported health complaints. Psychology and Aging, 27(4), 881-891. doi:10.1037/a0029125.