If you can access Haskett et al (2006) article it evaluates the factor structure and validity of the PSI short form and includes the items.
Haskett, M. E., Ahern, L. S., Ward, C. S., & Allaire, J. C. (2006). Factor Structure and Validity of the Parenting Stress Index-Short Form. Journal Of Clinical Child And Adolescent Psychology, 35(2), 302-312. doi:10.1207/s15374424jccp3502_14
I would add, though, that if it is copyrighted and now available through purchase only, you could run into problems if you publish this without purchasing it.
You can also access: L.A. Dardas & M. M. Ahmad. Psychometric properties of the Parenting Stress Index with parents of children with autistic disorder. Journal of Intellectual Disability Research, volume 58 part 6 pp 560–571 june 2014.