title: Erratum to: Evaluating the efficacy of a web-based self-help intervention with and without chat counseling in reducing the cocaine use of problematic cocaine users: the study protocol of a pragmatic three-arm randomized controlled trial.
authors.affiliation: Swiss Research Institute for Public Health and Addiction at the University of Zurich, Konradstrasse 32, Zurich, Switzerland. michael.schaub@isgf.uzh.ch.
authors.forename: Michael P
authors.initials: MP
authors.lastname: Schaub
authors.affiliation: Swiss Research Institute for Public Health and Addiction at the University of Zurich, Konradstrasse 32, Zurich, Switzerland.
authors.forename: Larissa J
authors.initials: LJ
authors.lastname: Maier
authors.affiliation: Swiss Research Institute for Public Health and Addiction at the University of Zurich, Konradstrasse 32, Zurich, Switzerland.
authors.forename: Andreas
authors.initials: A
authors.lastname: Wenger
authors.affiliation: Arud, Centres for Addiction Medicine, Konradstrasse 32, Zurich, 8005, Switzerland.
authors.forename: Lars
authors.initials: L
authors.lastname: Stark
authors.affiliation: Arud, Centres for Addiction Medicine, Konradstrasse 32, Zurich, 8005, Switzerland.
authors.forename: Oliver
authors.initials: O
authors.lastname: Berg
authors.affiliation: Arud, Centres for Addiction Medicine, Konradstrasse 32, Zurich, 8005, Switzerland.
authors.forename: Thilo
authors.initials: T
authors.lastname: Beck
authors.affiliation: Department of Psychiatry, Psychotherapy and Psychosomatics, Clinical and Experimental Pharmacopsychology, Psychiatric Hospital of the University of Zurich, Lenggstrasse 31, Zürich, 8032, Switzerland.
authors.forename: Boris B
authors.initials: BB
authors.lastname: Quednow
authors.affiliation: Swiss Research Institute for Public Health and Addiction at the University of Zurich, Konradstrasse 32, Zurich, Switzerland.
authors.forename: Severin
authors.initials: S
authors.lastname: Haug