** Hadjidimos, Apostolos
**
**Twins of Hofstadter elements, 18 (2018) 63--70.**

**
**** Hajja, Mowaffaq
**
** (with S. Abu-Saymeh) Triangle centers with linear intercepts and linear subangles, 5 (2005) 33--36.**

** (with S. Abu-Saymeh) Some Brocard-like points of a triangle, 5 (2005) 65--74. **

** (with M. Spirova) A characterization of the centroid using June Lester's shape function, 6 (2006) 53--55. **

**A very short and simple proof of ``the most elementary theorem" of euclidean geometry, 6 (2006) 167--169. **

** (with S. Abu-Saymeh) Coincidence of centers for scalene triangles, 7 (2007) 137--146. **

**A short trigonometric proof of the Steiner-Lehmus theorem, 8 (2008) 39--42. **

**A condition for a circumscriptible quadrilateral to be cyclic, 8 (2008) 103--106. **

** (with S. Abu-Saymeh and H. A. ShahAli) Another variation of the Steiner-Lehmus theme, 8 (2008) 131--140. **

**Stronger forms of the Steiner-Lehmus theorem, 8 (2008) 157--161. **

**
**** Hatzipolakis, Antreas
**
** (with F. M. van Lamoen, B. Wolk, and P. Yiu) Concurrency of four Euler lines, 1 (2001) 59--68. **

** (with P. Yiu) Pedal triangles and their shadows, 1 (2001) 81--90. **

** (with P. Yiu) Reflections in triangle geometry, 9 (2009) 301--348. **

**
**** Haugland, Jan Kristian
**
**A note on conic sections and tangent circles, 17 (2017) 1--12.**

**
**** Heindl, Gerhard
**
**How to compute a triangle with prescribed lengths of its internal angle bisectors, 16 (2016) 407--414.**

**
**** Helfgott, Michel
**
** (with G. Baloglou) Angles, area, and perimeter caught in a cubic, 8 (2008) 13--25. **

**
**** Hererra, Blas
**
**Two conjectures of Victor Thëbault linking tetrahedra with quadrics, 15 (2015) 115--122.**

**
**** Hess, Albrecht
**
**A highway from Heron to Brahmagupta, 12 (2012) 191--192. **

**Bicentric quadrilaterals through inversion, 13 (2013) 11--15.**

**On a circle containing the incenters of tangential quadrilaterals, 14 (2014) 389--396.**

**Transforming tripolar into barycentric coordinates, 15 (2015) 253--261.**

** (with D. Perrin and M. Trense) A group theoretic interpretation of Poncelet's theorem -- the real case, 16 (2016) 381--395. **

**A group theoretic interpretation of Poncelet's theorem, part 2: the complex case, 17 (2017) 255--272. **

**
**** Hoehn, Larry
**
**A new formula concerning the diagonals and sides of a quadrilateral, 11 (2011) 211--212. **

**The isosceles trapezoid and its dissecting similar triangles, 12 (2012) 29--38. **

**Derivation of the law of cosines via the incircle, 13 (2013) 133--153.**

**
**** Hoffmann, Miklos
**
** (with S. Gorjanc) On the generalized Gergonne point and beyond, 8 (2008) 151--155. **

**
**** Hofstetter, Kurt
**
**A simple construction of the golden section, 2 (2002) 65--66. **

**A 5-step division of a segment in the golden section, 3 (2003) 205--206. **

**Another 5-step division of a segment in the golden section, 4 (2004) 21--22. **

**Division of a segment in the golden section with ruler and rusty compass, 5 (2005) 135--136. **

**A 4-step construction of the golden ratio, 6 (2006) 179--180. **

**A simple ruler and rusty compass construction of the regular pentagon, 8 (2008) 61--62. **

**A simple compass-only construction of the regular pentagon, 8 (2008) 147--148. **

**
**** Holland, Finbarr
**
**Another verification of Fagnano's theorem, 7 (2007) 207--210. **

**
**** Holshouser, Arthur
**
** (with H. Reiter) Using complex weighted centroids to create homothetic polygons, 12 (2012) 247--251. **

** (with S. Molchanov and H. Reiter) Applying Poncelet's theorem to the pentagon and the pentagonal star, 16 (2016) 141--149. **

** (with S. Molchanov and H. Reiter) A special case of Poncelet's problem, 16 (2016) 151--170. **

** Homentcovschi, Laurentiu
**
** (with W. G. Boskoff and B. D. Suceava) Gossard's perspector and projective consequences, 13 (2013) 169--184.**

**
**** Honvault, Pascal
**
** (with T. Gensane) Optimal packings of two ellipses in a square, 14 (2014) 371--380.**

** Similarities on a sphere, 16 (2016) 313--316.**

**
**** Horwitz, Alan
**
** A ladder ellipse problem, 16 (2016) 63--67.**

**
**** Hudelson, Matthew
**
**Concurrent medians of (2n+1)-gons, 6 (2006) 139--147. **

**Formulas among diagonals in the regular polygon and the Catalan numbers, 6 (2006) 255--262. **

**
**** Hurley, Susan
**
** (with A. Fontaine) Proof by picture: Products and reciprocals of diagonals length ratios in the regular polygon, 6 (2006) 97--101. **

**
**** Hvala, Bojan
**
**Diophantine Steiner triples and Pythagorean-type triangles, 10 (2010) 93--97. **

**
**** Hwang, Minyoung
**
** (with C. W. Bae and J. H. Lee) Some loci in the animation of a Sangaku diagram, 16 (2016) 187--191.**

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