There are pictures of Mozes Loonstijn and Sara Biet published in D. Slier and I. Shine, Hidden letters, a glimpse of Holland during World War II (New York 2007) 99.
In addition, a Jokos file (number 13748) on this family is at the Amsterdam Municipal Archive. Access is subject to authorization from the Stichting Joods Maatschappelijk Werk.