In SLEEP Volume 37, Issue 7 page 1209 there was an error in the spelling of Dr. van Maanen's name. The correct spelling is:
J. Peter van Maanen
The citation for this paper should read:
van Maanen JP, de Vries N. Long-term effectiveness and compliance of positional therapy with the Sleep Position Trainer in the treatment of positional obstructive sleep apnea syndrome. SLEEP 2014;37(7):1209-1215.
There is also a correction to the first sentence in the interventions section of the abstract on page 1209. It should read:
Patients were asked to use the SPT for 6 mo.