1821
Lituites imperfectus — Wahlenberg, pp. 84
1845
Lituites imperfectus — Quenstedt, fig. 2:17
1849
Lituites imperfectus — Quenstedt, pp. 51, fig. 2:3a,b
1860
Estonioceras imperfectum — Lossen, pp. 20
1891
Estonioceras imperfectum — Schröder, pp. 37, fig. III 2; IV 3-4
1905
Estonioceras imperfectum — Lamansky, pp. 81
1953
Estonioceras imperfectum (Quenstedt, 1846) — Balashov, pp. 220-222, fig. 2:1-3
1959
Estonioceras imperfectum — Sweet, pp. 299
1964
Estonioceras imperfectum — Chang, pp. 132-133, 138, fig. 1:5
1971
Estonioceras imperfectum — Neben & Krüger, fig. 18:4
2005
Estonioceras imperfectum (Quenstedt, 1845) — Kröger & Mutvei, pp. 787, fig. text fig. 2D-F, 5E
2013
Estonioceras imperfectum — Mutvei, pp. 174, fig. 2
2014
Estonioceras imperfectum — King, fig. 1C