7 (English Wikipedia)

Heyden, Anders; Sparr, Gunnar; Nielsen, Mads; Johansen, Peter (2003-08-02). Computer Vision – ECCV 2002: 7th European Conference on Computer Vision, Copenhagen, Denmark, May 28–31, 2002. Proceedings. Part II. Springer. p. 661. ISBN 978-3-540-47967-3. A frieze pattern can be classified into one of the 7 frieze groups...
Dallas, Elmslie William (1855). "Part II. (VII): Of the Circle, with its Inscribed and Circumscribed Figures − Equal Division and the Construction of Polygons". The Elements of Plane Practical Geometry. London: John W. Parker & Son, West Strand. p. 134.
"...It will thus be found that, including the employment of the same figures, there are seventeen different combinations of regular polygons by which this may be effected; namely, —

When three polygons are employed, there are ten ways; viz., 6,6,6 – 3.7.42 — 3,8,24 – 3,9,18 — 3,10,15 — 3,12,12 — 4,5,20 — 4,6,12 — 4,8,8 — 5,5,10.

With four polygons there are four ways, viz., 4,4,4,4 — 3,3,4,12 — 3,3,6,6 — 3,4,4,6.

With five polygons there are two ways, viz., 3,3,3,4,4 — 3,3,3,3,6.

With six polygons one way — all equilateral triangles [ 3.3.3.3.3.3 ]."
Note: the only four other configurations from the same combinations of polygons are: 3.4.3.12, (3.6)², 3.4.6.4, and 3.3.4.3.4.
Antoni, F. de; Lauro, N.; Rizzi, A. (2012-12-06). COMPSTAT: Proceedings in Computational Statistics, 7th Symposium held in Rome 1986. Springer Science & Business Media. p. 13. ISBN 978-3-642-46890-2. ...every catastrophe can be composed from the set of so called elementary catastrophes, which are of seven fundamental types.

britannica.com

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dailysabah.com

Ergil, Leyla Yvonne (2021-06-10). "Turkey's talisman superstitions: Evil eyes, pomegranates and more". Daily Sabah. Retrieved 2023-04-05.

diale.org

Császár, Ákos (1949). "A polyhedron without diagonals" (PDF). Acta Scientiarum Mathematicarum (Szeged). 13: 140–142. Archived from the original (PDF) on 2017-09-18.

doi.org

"Nāṣir-i Khusraw", An Anthology of Philosophy in Persia, I.B.Tauris, 2001, doi:10.5040/9780755610068.ch-008, ISBN 978-1-84511-542-5, retrieved 2020-11-17

ebooks.edu.gr

"Μαθηματικά Α' Δημοτικού" [Mathematics for the First Grade] (PDF) (in Greek). Ministry of Education, Research, and Religions. p. 33. Retrieved May 7, 2018.

gizmodo.com

Gonzalez, Robbie (4 December 2014). "Why Do People Love The Number Seven?". Gizmodo. Retrieved 20 February 2022.

gruze.org

Jardine, Kevin. "Shield - a 3.7.42 tiling". Imperfect Congruence. Retrieved 2023-01-09. 3.7.42 as a unit facet in an irregular tiling.

iltalehti.fi

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researchgate.net

Kubovy, Michael; Psotka, Joseph (May 1976). "The predominance of seven and the apparent spontaneity of numerical choices". Journal of Experimental Psychology: Human Perception and Performance. 2 (2): 291–294. doi:10.1037/0096-1523.2.2.291. Retrieved 20 February 2022.

santeriachurch.org

Yemaya. Santeria Church of the Orishas. Retrieved 25 November 2022

scientificamerican.com

Bellos, Alex. "The World's Most Popular Numbers [Excerpt]". Scientific American. Retrieved 20 February 2022.

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tekniikkatalous.fi

Eeva Törmänen (September 8, 2011). "Aamulehti: Opetushallitus harkitsee numero 7 viivan palauttamista". Tekniikka & Talous (in Finnish). Archived from the original on September 17, 2011. Retrieved September 9, 2011.

ucr.edu

upc.es

Szilassi, Lajos (1986). "Regular toroids" (PDF). Structural Topology. 13: 74. Zbl 0605.52002.

urantia.org

web.archive.org

Eeva Törmänen (September 8, 2011). "Aamulehti: Opetushallitus harkitsee numero 7 viivan palauttamista". Tekniikka & Talous (in Finnish). Archived from the original on September 17, 2011. Retrieved September 9, 2011.
"Education writing numerals in grade 1." Archived 2008-10-02 at the Wayback Machine(Russian)
Császár, Ákos (1949). "A polyhedron without diagonals" (PDF). Acta Scientiarum Mathematicarum (Szeged). 13: 140–142. Archived from the original (PDF) on 2017-09-18.
Massey, William S. (December 1983). "Cross products of vectors in higher dimensional Euclidean spaces" (PDF). The American Mathematical Monthly. 90 (10). Taylor & Francis, Ltd: 697–701. doi:10.2307/2323537. JSTOR 2323537. S2CID 43318100. Zbl 0532.55011. Archived from the original (PDF) on 2021-02-26. Retrieved 2023-02-23.
"Poincaré Conjecture | Clay Mathematics Institute". 2013-12-15. Archived from the original on 2013-12-15. Retrieved 2020-08-25.

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Weisstein, Eric W. "Double Mersenne Number". mathworld.wolfram.com. Retrieved 2020-08-06.
Weisstein, Eric W. "Heptagon". mathworld.wolfram.com. Retrieved 2020-08-25.
Weisstein, Eric W. "7". mathworld.wolfram.com. Retrieved 2020-08-07.
Weisstein, Eric W. "Dice". mathworld.wolfram.com. Retrieved 2020-08-25.

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7 (English Wikipedia)

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