Bardsley, P. A., Bentley, S., Hall, H. S., Singh, S. J., Evans, D. H., & Morgan, M. D. (1993). Measurement of inspiratory muscle performance with incremental threshold loading: A comparison of two techniques.

Bardsley, P A., S. Bentley, H S. Hall, S J. Singh, D H. Evans, and M D. Morgan. Measurement of Inspiratory Muscle Performance With Incremental Threshold Loading: A Comparison of Two Techniques. 1993.

Bardsley, P A., et al. Measurement of Inspiratory Muscle Performance With Incremental Threshold Loading: A Comparison of Two Techniques. 1993.