Helmut Schaefer

9.1k total citations · 4 hit papers
72 papers, 5.7k citations indexed

About

Helmut Schaefer is a scholar working on Mathematical Physics, Computational Theory and Mathematics and Applied Mathematics. According to data from OpenAlex, Helmut Schaefer has authored 72 papers receiving a total of 5.7k indexed citations (citations by other indexed papers that have themselves been cited), including 34 papers in Mathematical Physics, 16 papers in Computational Theory and Mathematics and 14 papers in Applied Mathematics. Recurrent topics in Helmut Schaefer's work include Advanced Banach Space Theory (30 papers), Approximation Theory and Sequence Spaces (13 papers) and Advanced Topics in Algebra (11 papers). Helmut Schaefer is often cited by papers focused on Advanced Banach Space Theory (30 papers), Approximation Theory and Sequence Spaces (13 papers) and Advanced Topics in Algebra (11 papers). Helmut Schaefer collaborates with scholars based in Germany, United States and Poland. Helmut Schaefer's co-authors include M. S. Ramanujan, Manfred Wolff, Ulf Schlotterbeck, Rainer Nagel, Wolfgang Arendt, Xiao Dong Zhang, Werner J. Ricker, Manfred Rudolph, Dieter Bergner and Xiao‐Dong Zhang and has published in prestigious journals such as Transactions of the American Mathematical Society, American Mathematical Monthly and Numerische Mathematik.

In The Last Decade

Helmut Schaefer

68 papers receiving 4.6k citations

Hit Papers

Topological Vector Spaces. 1955 2026 1978 2002 1967 1974 1971 1955 500 1000 1.5k 2.0k 2.5k
What are hit papers?

Hit papers significantly outperform the citation benchmark for their cohort. A paper qualifies if it has ≥500 total citations, achieves ≥1.5× the top-1% citation threshold for papers in the same subfield and year (this is the minimum needed to enter the top 1%, not the average within it), or reaches the top citation threshold in at least one of its specific research topics.

  1. Topological Vector Spaces.
    1967 2.6k citations Helmut Schaefer et al. profile →
  2. Banach Lattices and Positive Operators
    1974 1.4k citations Helmut Schaefer profile →
  3. Topological Vector Spaces
    1971 754 citations Helmut Schaefer profile →
  4. �ber die Methode der a priori-Schranken
    1955 206 citations Helmut Schaefer Mathematische Annalen profile →

Peers — A (Enhanced Table)

Peers by citation overlap · career bar shows stage (early→late) cites · hero ref

Name h Career Trend Papers Cites
Helmut Schaefer Germany 17 3.3k 2.4k 1.7k 1.3k 960 72 5.7k
Edwin Hewitt United States 30 4.7k 1.4× 2.9k 1.2× 1.7k 1.0× 2.6k 2.0× 702 0.7× 105 8.7k
M. S. Ramanujan United States 11 1.6k 0.5× 1.1k 0.4× 860 0.5× 789 0.6× 445 0.5× 44 2.9k
W. J. Thron United States 22 1.1k 0.3× 1.6k 0.7× 1.5k 0.9× 1.1k 0.8× 208 0.2× 87 4.7k
N. J. Kalton United States 37 4.1k 1.3× 3.6k 1.5× 745 0.4× 932 0.7× 1.3k 1.3× 220 5.3k
Joram Lindenstrauss Israel 41 6.8k 2.1× 5.0k 2.1× 1.8k 1.1× 2.3k 1.8× 2.6k 2.7× 112 9.0k
R. R. Phelps United States 27 1.8k 0.5× 1.3k 0.5× 1.7k 1.0× 1.0k 0.8× 415 0.4× 57 3.3k
M. Г. Крейн Germany 23 2.6k 0.8× 2.6k 1.1× 2.2k 1.3× 460 0.4× 314 0.3× 53 5.7k
T. W. Gamelin United States 23 1.8k 0.5× 2.1k 0.9× 591 0.4× 861 0.7× 309 0.3× 60 3.5k
Kenneth A. Ross United States 21 3.2k 1.0× 1.5k 0.6× 840 0.5× 2.2k 1.7× 319 0.3× 91 5.5k
Ivan Singer Romania 25 1.1k 0.4× 922 0.4× 1.6k 0.9× 721 0.6× 538 0.6× 135 3.3k

Countries citing papers authored by Helmut Schaefer

Since Specialization
Citations

This map shows the geographic impact of Helmut Schaefer's research. It shows the number of citations coming from papers published by authors working in each country. You can also color the map by specialization and compare the number of citations received by Helmut Schaefer with the expected number of citations based on a country's size and research output (numbers larger than one mean the country cites Helmut Schaefer more than expected).

Fields of papers citing papers by Helmut Schaefer

Since Specialization
Physical SciencesHealth SciencesLife SciencesSocial Sciences

This network shows the impact of papers produced by Helmut Schaefer. Nodes represent research fields, and links connect fields that are likely to share authors. Colored nodes show fields that tend to cite the papers produced by Helmut Schaefer. The network helps show where Helmut Schaefer may publish in the future.

Co-authorship network of co-authors of Helmut Schaefer

This figure shows the co-authorship network connecting the top 25 collaborators of Helmut Schaefer. A scholar is included among the top collaborators of Helmut Schaefer based on the total number of citations received by their joint publications. Widths of edges represent the number of papers authors have co-authored together. Node borders signify the number of papers an author published with Helmut Schaefer. Helmut Schaefer is excluded from the visualization to improve readability, since they are connected to all nodes in the network.

All Works

20 of 20 papers shown
1.
Haase, Markus & Helmut Schaefer. (2011). ChemInform Abstract: Upconverting Nanoparticles. ChemInform. 42(35). 1 indexed citations
2.
Schaefer, Helmut. (1994). VDI-Lexikon Energietechnik. 2 indexed citations
3.
Schaefer, Helmut & Xiao Dong Zhang. (1994). A note on order bounded vector measures. Archiv der Mathematik. 63(2). 152–157. 4 indexed citations
4.
Schaefer, Helmut. (1992). On convex hulls. Archiv der Mathematik. 58(2). 160–163. 1 indexed citations
5.
Schaefer, Helmut. (1989). On order continuous linear operators. Indagationes Mathematicae (Proceedings). 92(4). 479–483. 2 indexed citations
6.
Nagel, Rainer, et al.. (1986). Aspects of Positivity in Functional Analysis. 122. 38 indexed citations
7.
Schaefer, Helmut. (1982). A metric variant of Frobenius's theorem and some other remarks on positive matrices. Linear Algebra and its Applications. 42. 175–182. 1 indexed citations
8.
Bergner, Dieter, et al.. (1975). Neue Langzeit‐Titananoden für die Alkalichlorid‐Elektrolyse. Chemie Ingenieur Technik. 47(4). 136–137. 6 indexed citations
9.
Schaefer, Helmut & Ulf Schlotterbeck. (1975). On the approximation of kernel operators by operators of finite rank. Journal of Approximation Theory. 13(1). 33–39. 1 indexed citations
10.
Schaefer, Helmut. (1973). Tausend Zweifarbfledermäuse (Vespertilio murinus L.) aus der Hohen Tatra — Nachweis an Unterkiefern. Biodiversity Heritage Library (Smithsonian Institution). 2 indexed citations
11.
Schaefer, Helmut. (1971). On the characteristic roots of real matrices. Proceedings of the American Mathematical Society. 28(1). 91–92.
12.
Schaefer, Helmut. (1970). Eine Abschätzung der nichttrivialen Eigenwerte stochastischer Matrizen. Numerische Mathematik. 15(3). 219–223. 5 indexed citations
13.
Schaefer, Helmut. (1966). �ber das Randspektrum positiver Operatoren. Mathematische Annalen. 162(3). 289–293. 5 indexed citations
14.
Schaefer, Helmut. (1962). �ber die Additivit�t von Spektralma�en. Mathematische Zeitschrift. 79(1). 456–459. 1 indexed citations
15.
Schaefer, Helmut. (1960). Some spectral properties of positive linear operators. Pacific Journal of Mathematics. 10(3). 1009–1019. 73 indexed citations
16.
Schaefer, Helmut. (1959). Zur komplexen Erweiterung linearer R�ume. Archiv der Mathematik. 10(1). 363–365.
17.
Schaefer, Helmut. (1959). On nonlinear positive operators. Pacific Journal of Mathematics. 9(3). 847–860. 36 indexed citations
18.
Schaefer, Helmut. (1958). Halbgeordnete lokalkonvexe Vektorr�ume. Mathematische Annalen. 135(2). 115–141. 25 indexed citations
19.
Schaefer, Helmut. (1957). Über die Methode sukzessiver Approximationen.. 59. 131–140. 65 indexed citations
20.
Schaefer, Helmut. (1955). �ber die Methode der a priori-Schranken. Mathematische Annalen. 129(1). 415–416. 206 indexed citations breakdown →

Rankless uses publication and citation data sourced from OpenAlex, an open and comprehensive bibliographic database. While OpenAlex provides broad and valuable coverage of the global research landscape, it—like all bibliographic datasets—has inherent limitations. These include incomplete records, variations in author disambiguation, differences in journal indexing, and delays in data updates. As a result, some metrics and network relationships displayed in Rankless may not fully capture the entirety of a scholar's output or impact.

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