After the appearance of the article “A retrospective on 60 years of approximation theory and associated fields” (J. Approx. Theory 160 (1–2) (2009) 3–18), several readers informed me (PLB) that they would like to see an article based upon research contacts and conference participations of members of the chair “Lehrstuhl A für Mathematik” at Aachen throughout the world. The present paper is devoted to the research visits of members of the Aachen research group to America and Western Europe. The countries covered are USA and Canada, Austria, Netherlands, Belgium, Switzerland, Sweden, England and Scotland, Italy, Spain, Portugal, Norway, Greece, and Ireland.

在出现“回顾60年的近似理论和相关领域”（J.近似理论160（1-2）（2009）3-18）一文之后，几位读者告诉我（PLB）他们想在全球亚琛的“ Lehrstuhl AfürMathematik”主持人的研究联系和会议参与下看到一篇文章。本文致力于亚琛研究小组成员对美国和西欧的研究访问。涵盖的国家是美国和加拿大，奥地利，荷兰，比利时，瑞士，瑞典，英国和苏格兰，意大利，西班牙，葡萄牙，挪威，希腊和爱尔兰。