1821
Entomostracites crassicauda Wahlenberg, 1821 — Wahlenberg, pp. 294, fig. 7: 6
1827
Asaphus (Illaenus) crassicauda Wahlenberg, 1821 — Dalman, pp. 250, fig. 5: 2a-f
1829
Trilobites Esmarkii Schlotheim, 1826 — Boeck, pp. 40
1835
Illaenus crassicauda Wahlenberg, 1821 — Sars, pp. 341, fig. 9:10
1837
Illaenus crassicauda Wahlenberg, 1821 — Hisinger, pp. 17, fig. 3: 5 ?
1854
Illaenus crassicauda Wahlenberg, 1821 — Angelin, pp. 41, fig. 24: 2, 2a ?
1880
Illaenus Dalmani Volborth, 1863 — Holm, pp. 16
1882
Illaenus Dalmani Volborth, 1863 — Brögger, pp. 97
1882
Illaenus Esmarkii (Schlotheim, 1826) — Holm, pp. 55, fig. 6: 8
1886
Illaenus Esmarkii (Schlotheim, 1826) — Holm, pp. 47-54, fig. 1: 1-6
1901
Illaenus Esmarkii Schlotheim, 1826 — Lindström, pp. 58, fig. 4: 26-30
1905
Illaenus Esmarkii Schlotheim, 1826 — Lamansky, pp. 57, 169
1907
Illaenus Esmarkii Schlotheim, 1826 — Schmidt, pp. 46
1934
Illaenus esmarkii Schlotheim, 1826 — Störmer, pp. 331
1936
Illaenus Esmarkii Schlotheim, 1826 — Siegfried, pp. 24, fig. 7a; 8: 2
1941
Illaenus esmarkii Schlotheim, 1826 — Störmer, pp. 116, 125, fig. 4
1954
Illaenus sarsi n. sp. — Jaanusson, pp. 575, fig. 2: 1-3
1957
Illaenus sarsi Jaanusson, 1957 — Jaanusson, pp. 114-123, fig. 4: 1-9
1973
Illaenus sarsi Jaanusson, 1957 — Bergström, fig. 5: 5-6
1976
Illaenus sarsi Jaanusson, 1957 — Reyment, pp. 10, fig. 28a-b
1980
Illaenus sarsi Jaanusson, 1957 — Tjernvik & Johansson, pp. 194
1995
Illaenus sarsi Jaanusson, 1957 — Nielsen, pp. 337-339, fig. 243