Here are three ways to access the paper J.M. Swart (2016): A simple proof of exponential decay of subcritical contact processes.

• Probab. Theory Relat. Fields (2016). doi:10.1007/s00440-016-0741-1 (A link that allows for free online viewing of the published paper, but not for dowloading)
• The final publication is available at Springer via http://dx.doi.org/10.1007/s00440-016-0741-1 (According to one set of Springer rules, I am legally bound to set a link using exactly this phrase.)
• Swart, J.M. Probab. Theory Relat. Fields (2016). doi:10.1007/s00440-016-0741-1 (A link to the online publication according to the instructions there)