Report (2018) - A. Van Keulen (author), Fred Keulen (author), A. van Keulen (author), Fred Van Keulen (author), Fred van Van Keulen (author), A Keulen (author), F Keulen (author), F. Keulen (author), Fred van Keulen (author), F. Van Keulen (author), Fred van Keulen (author), F van Keulen (author), A van Keulen (author), A. Keulen (author), A Van Keulen (author), F Van Keulen (author), Fred van van Keulen (author), F. van Keulen (author), A.W.M. Ahsmann (author), Evert van den Akker (author), Milou Habraken (author), Paul Burghardt (author), Bayu Jayawardhana (author), Harro Van Lente (author), Timo Meinders (author), Bert Thuis (author), ? et al (author), ? ... [et Al] (author), et. al. (author), et. et al (author), et. ... [et Al] (author), ? al. (author)