覆面算

https://www.math.uni-bielefeld.de/~sillke/PUZZLES/ALPHAMETIC/alphametic-mike-keith.html

https://www.math.uni-bielefeld.de/~sillke/PUZZLES/ALPHAMETIC/

http://bach.istc.kobe-u.ac.jp/llp/crypt.html

http://www.tkcs-collins.com/truman/alphamet/alphamet.shtml

https://web.math.sinica.edu.tw/math_media/d234/23403.pdf

http://goodprimes.eu5.org/GSum.htm

http://www.yottkp.edu.hk/CustomPage/43/17leaf.pdf

http://www2.kuas.edu.tw/prof/cjh/2003puzzle/subject/index13.htm

http://www.primepuzzle.com/leeslatest/alphameticpuzzles.html

http://www.contestcen.com/rithms.htm

http://www.contestcen.com/index.htm

https://www.math.ubc.ca/~israel/applet/metic/metic.html

http://cryptarithms.awardspace.us/links.html

http://colin.barker.pagesperso-orange.fr/crypta.htm#Index

http://rsd2-alert-durden-connections.weebly.com/cryptarithms.html

http://www.cross-plus-a.com/help.htm

https://www.crsd.org/Page/46263

http://udel.edu/~tomkeane/sendmoremoney.html

http://cryptarithms.awardspace.us/primer.html

https://www.ixl.com/math/

https://www.ixl.com/?partner=google&campaign=55761185&adGroup=2210422625&gclid=CjwKCAiA1L_xBRA2EiwAgcLKAyXzWJ1iBGije3baDCFfVJEcPnUDa5g-dwPRYFESn-vqBJ722RFzxBoCD6sQAvD_BwE

http://www.dr-mikes-math-games-for-kids.com/cryptarithms.html

http://www.magic-squares.net/number_patterns_index.htm

http://mathforum.org/library/drmath/view/66868.html

http://untilheaven.tripod.com/id112.htm(oeis sequences)

http://people.missouristate.edu/lesreid/Past.html

http://www.shyamsundergupta.com/

https://www2.stetson.edu/~efriedma/mathmagic/0608.html

http://www.mathland.idv.tw/

http://www.mrob.com/pub/

http://www.mrob.com/pub/seq/

http://goodprimes.eu5.org/

http://www.worldofnumbers.com/index.html