Pings, V. M. (1976). Reference Services Accountability and Measurement.
Citazione stile Chigago Style (17a edizione)Pings, Vern M. Reference Services Accountability and Measurement. 1976.
Citatione MLA (9a ed.)Pings, Vern M. Reference Services Accountability and Measurement. 1976.
Attenzione: Queste citazioni potrebbero non essere precise al 100%.