B. Ainsworth, The compendium of physical activities tracking guide, 2002.

L. Bao and S. S. Intille, Activity Recognition from User-Annotated Acceleration Data, 2nd International Conference on Pervasive Computing, 2004.
DOI : 10.1007/978-3-540-24646-6_1

N. Bidargaddi, A. Sarela, L. Klingbeil, and M. Karunnanithi, Detecting walking activity in cardiac rehabilitation by using accelerometer, 2007 3rd International Conference on Intelligent Sensors, Sensor Networks and Information, 2007.
DOI : 10.1109/ISSNIP.2007.4496903

R. Diemer and J. Kreuzer, Multi-Sensorplattform for Activity Measurements, International Conference on Ambulatory Monitoring of Physical Activity and Movements, 2008.

R. K. Ibrahim, E. Ambikairajah, B. G. Cellar, and N. H. Lovell, Time-Frequency Based Features for Classification of Walking Patterns, 2007 15th International Conference on Digital Signal Processing, 2007.
DOI : 10.1109/ICDSP.2007.4288550

N. Ravi, N. Dandekar, P. Mysore, L. Littman, and M. , Activity recognition from accelerometer data, American Association for Artificial Intelligence, 2005.