some random collections of links to my sites. (this page is not up-to-date. Most links here are ancient.)

see also Printed Citations to Xah Lee Site

XahLee.org has 7 thousand visitors per day, and is ranked by Alexa.com as the 70k most popular sites of all world's sites. Or, about 40k in North America.

Below are some selected links that may be noteworthy, in no particular order. Some may have gone defunct.

Here are the essays that have appeared on Hacker News:

- 2010-07-13 ErgoEmacs features. news.ycombinator.com
- 2010-04-13 Paul Graham's Infatuation with the Concept of Hacker. news.ycombinator.com
- 2010-03-12 Why Emacs is Still so Useful Today. news.ycombinator.com
- 2009-02-04 Why Software Suck. news.ycombinator.com
- 2009-01-30 “Ask PG: What is the list of banned sites and why are they banned?”. Source
- 2008-06-04 “Effective Emacs - "Nobody has been using Emacs longer than I have"” news.ycombinator.com
- 2007-04-07 Sorting in Python ＆ Perl. news.ycombinator.com

There are about 20 or so posts mentioning my name or site. See: Google searh “site:news.ycombinator.com xah lee”.

See also: Hacker News, Xahlee.org, and What is Politics?.

XahLee.org on Reddit: http://www.reddit.com/domain/xahlee.org/

Here's Reddit's widget showing the top 10 “hottest” links to xahlee.org:

XahLee.org on Delicious: http://delicious.com/search?p=site:xahlee.org. (Local copy as of 2006-03: delicious_200603.zip)

Some of my emacs lisp tutorial have been translated to Chinese and Japanese.

- Emacs Lisp Idioms (for writing interactive commands) in Japanese: 〔武蔵の日記 (Musashi's Diary) By 武蔵. @ http://d.hatena.ne.jp/sirocco634/20090118〕
- Emacs Lisp Basics in Chinese: 〔[elisp] EmacsLisp 基础 By laihj. @ http://www.laihj.net/2010/01/elipsemacslisp-basi/〕

〔Astroid as Catacaustic of Deltoid By John Baez (American Mathematical Society Blog). @ blogs.ams.org…〕

“Yahoo!” has my curve sites in their math and science dictionary section, since about 1996.

~~http://www.yahoo.com/science/dictionaries/~~~~http://www.yahoo.com/science/mathematics/geometry/~~(Local copy as of 2006-03: yahoo_dir_200603.zip)

Google directory has page links to my site under geometry section:

~~http://directory.google.com/Top/Science/Math/Geometry/~~~~http://directory.google.com/Top/Science/Math/Geometry/Software~~

Local copies as of 2006-03: google_dir_200603.zip

Netscape's dmoz Open Directory Project has page links to my site under geometry section: http://dmoz.org/Science/Math/Geometry/Plane_Geometry (Local copy as of 2006-03: dmoz_org_200603.zip)

USPatentInfo.com has my curve site in reference section: http://www.uspatentinfo.com/patentInfoResources_dic.html . The page existed at least form 2003-12 to 2005-03. (Local copy as of 2003-12 us_patent_200312.zip (text version: us_patent_resources_2003.txt), from web.archive.org as of 2006-03)

〈MacTutor History of Mathematics Archive〉 is from the St. Andrew University of Scotland. They are one of the first large site covering mathematics and in particular math history. Very well-known as early as 1995, and probably still is the best math history site as of 2006. They have a Famous Curves Index project, which is a exposition over some 60 plane curves and their history. Almost every page has a link to one of my pages of plane curves. http://www-history.mcs.st-andrews.ac.uk/%7Ehistory/Curves/Curves.html

Here's is a comprehensive page of their external links: http://www-history.mcs.st-andrews.ac.uk/%7Ehistory/External/external_links.html (local copy as of 2006-03: www-history_mcs_st-andrews_ac_uk_200603.zip).

The Math Forum is originally known as Geometry Forum, and is originally hosted and associated with Swarthmore College (PA, USA). They focus on high-school and college level math education. They are the very first website to have huge collection of math materials, as early as 1995. For a period of time from about 2000 to 2002, they invited me to host my website on their server free of charge. My website xahlee.org was hosted by them in this period. (before 2000-01, i do not have dedicated domain name, and my website wast hosted by www.best.com/~xah starting about 1996-02. Best.com is a tiny hosting company located in Mountain View, CA, USA. Around 1998 they are bought by verio.com.

Math Forum is acquired by Drexel University sometimes in 2000s.

One of the thing Math Forum do is to collect math resources on the web, and they are the earliest if not the first to have a comprehensive link database of math materials on the web. (In the mid 1990s, search engines are not there yet) They have several links to my site before my site was hosted by them.

- Selected site on the subject of Transformational Geometry: http://forum.swarthmore.edu/library/browse/static/topic/transform_g.html
- Selected Geometry Sites. http://forum.swarthmore.edu/geometry/selected.geom.html
- Selected site on conic sections. http://forum.swarthmore.edu/library/browse/static/topic/conic_g.html
- Math Forum Internet News. Vol.2, No.24 (16 June 1997). http://forum.swarthmore.edu/electronic.newsletter/mf.intnews2.24.html

(local copy as of 2006-03: mathforum_200603.zip)

The Textile Museum, in this online exhibition: Symmetry and Pattern: The Art of Oriental Carpets. (1997 〜 2005) by The Textile Museum and The Math Forum @ Drexel, at: http://mathforum.org/geometry/rugs/resources/links.html. Local copy as of 2006-06 mathforum_textile_museum.zip, contains a link to my Wallpaper Exposition.

The Geometry Center is a mathematics research and education center at the University of Minnesota. Geometry Center went out of funds around 1998, and now part of it became scienceu.com

Computer Software for Tiling, Compiled by Doris Schattschneider, Moravian College http://www.geom.uiuc.edu/software/tilings/TilingSoftware.html (local copy as of 2006-03: geo_center_200603.zip)

scienceu.com on tiling http://www.scienceu.com/geometry/articles/tiling/refs.html (Local copy os of 2006-03: scienceu_200603.zip)

Canadian Mathematical Society's Knot a Braid of Links selects a quality math site each week, since about 1997 or earlier. The quality or depth of their selected site varies.

My Visual Dictionary of Special Plane Curve was selected in 1996-04, and my WallPaper Groups is selected in 1997-11.

Their site around 2000 used to be at
~~http://www.camel.math.ca/Recreation/kabol/96best.html~~
~~http://www.math.ca/cgi/kabol/search.pl~~
(local copy as of knot_links_200603.zip)

National Taiwan University (台大數學)'s online Math Links section contains 2 links to my site. One to my Plane Curves project and one to my Wallpaper Groups project. These links existed in circa 2001 to .
~~http://www.math.ntu.edu.tw/link/math_field_geo.htm~~
(Local copy)

National Engineering Education Delivery System (
~~http://www1.needs.org/database/records/courseware/448.html~~.)

GeoGebra is a award-winning geometry software. They linked to my curve site for the many use of the software on my site as a demo of the software. http://www.geogebra.org/trac/wiki/Implicit/Reading

(Professor) Mathematician Dave Rusin's THE MATHEMATICAL ATLAS. Dave Rusin is a math professor at the Northern Illinois University. His “atlas” is a very useful overview of modern mathematics. He has a link to my WallPaper Groups at the groups category: http://www.math.niu.edu/~rusin/known-math/index/20-XX.html. (begin aroun 1999 ~ 2004-01) (local copy as of 2006-03: Dave_Rusin_200603.zip)

(Professor) Mathematician Richard Palais's surface gallery page. http://3d-xplormath.org/TopLevel/links.html (local copy as of 2006-03: vmm_math_uci_edu_200603.zip).

This link existed starting about 1998. Richard Palais has since became a personal friend, and i have become a member of his 3D-XplorMath Consortium.

(Professor) Mathematician David Eppstein's Geometry Junkyard (url collection) has 9 links to my site. http://www.ics.uci.edu/~eppstein/junkyard/index.html (localy copy as of 2006-03: geo_junkyard_200603.zip)

There are many more especially from professiors and universities, but it's time consuming to add them here.

I used to main all links to my site. In late 1990s, there are thousands of links to my site, from personal sites to educational institutions, mostly on my Visual Dictionary of Special Plane Curves and other math materials. In each month, i would process my web log and list new links to my site. Here's a 2000 Jan version of this page, which contained new links i found in the previous month, and it contains over 2000 links. linksToMySite_200001.html.gz. See the same page at internet archive: http://web.archive.org/web/20000817202924/http://www.xahlee.org/PageTwo_dir/Bookmarks_dir/linksToMySite.html

See also:

- Google Search links to XahLee.org
- http://www.google.com/search?q=link%3Axahlee.info+-site%3Axahlee.info+-site%3Axahlee.blogspot.com
- http://www.google.com/search?q=link%3Aergoemacs.org+-site%3Aergoemacs.org+-site%3Axahlee.blogspot.com

Discovered another citation to my Wallpaper groups: The 17 Wallpaper Groups work.

Chapter 1 Symmetry Groups Mathematics in Art and Architecture GEK1518 Helmer Aslaksen Department of Mathematics National University of Singapore aslaksen@math.nus.edu.sg www.math.nus.edu.sg/aslaksen/ Symmetry and Patterns

At Source www.math.nus.edu.sg.

More links:

- Trochoids: Curves Generated by a Rolling Circle By Christopher J Henrich. @ userpages.monmouth.com…. Links to:Visual Dictionary of Special Plane Curves.
- Home page of Davide Alessandro Reduzzi (Math 33A, lec. 3 – Linear Algebra and Applications) By Davide Alessandro Reduzzi. @ www.math.ucla.edu…. Links to Conic Sections

some links to xahlee.org math:

- MATH 741: Spectral geometry of random metrics By Dmitry Jakobson. McGill University. Source www.math.mcgill.ca. Links to Visual Dictionary of Special Plane Curves.
- Math 214 - Differential Manifolds, Fall 2010 By Jonathan Dahl. UC Berkeley. Source math.berkeley.edu. Links to Gallery of Famous Surfaces
- Supplements to some chapters of Experiencing Geometry By David W Henderson. Cornell University. math.cornell.edu. Links to Inversion.