Is performance anxiety a negative or positive attribute ? - Psychology bibliographies - in Harvard style

In-text: (Charlene and Andrews, 2009)

Your Bibliography: Charlene, R. and Andrews, N., 2009. An Investigation into the Choral Singer's Experience of Music Performance Anxiety. Journal of Research in Music Education, [online] 57(2), pp.109-110. Available at: <http://www.jstor.org/discover/10.2307/40204954?sid=21105514311871&uid=389499781&uid=3&uid=2134&uid=3738032&uid=60&uid=70&uid=389499791&uid=2> [Accessed 3 March 2015].

In-text: (Lehrer, 1995)

Your Bibliography: Lehrer, P. ed., 1995. Performance anxiety and how to control it: a psychologist's perspective. 1st ed. London: Kahn & Averill, pp.134-138.

In-text: (Zdzinski, 2011)

Your Bibliography: Zdzinski, S., 2011. A Response to Yaroslav Senyshyn and Susan A. O'Neill, "Subjective Experience of Anxiety and Musical Performance: A Relational Perspective. Philosophy of Music education review, [online] 9(1), pp.64-65. Available at: <http://www.jstor.org/discover/10.2307/40495457?sid=21105514311871&uid=60&uid=389499781&uid=3738032&uid=2134&uid=3&uid=389499791&uid=70&uid=2> [Accessed 3 March 2015].