Africk, Henry. Elementary College Geometry. CUNY Academic Works, 2013. https://academicworks.cuny.edu/ny_oers/6
Bard, Gregory V. Sage for Undergraduates. American Mathematical Society, 2015. http://www.gregorybard.com/books (CH, Nov’15, 53-1319).
Beck, Matthias, et al. A First Course in Complex Analysis. 2017. http://math.sfsu.edu/beck/complex.html
Beezer, Robert A. A First Course in Linear Algebra. Congruent Press, 2015. http://linear.ups.edu
Boelkins, Matthew, David Austin, and Steven Schlicker. Active Calculus. 2017. https://activecalculus.org
Bogart, Kenneth P. Combinatorics through Guided Discovery. 2017. https://bogart.openmathbooks.org
Brin, Leon Q. Tea Time Numerical Analysis. 2nd ed. Southern Connecticut State University, 2016. https://lqbrin.github.io/tea-time-numerical
Bruckner, Andrew M., Brian S. Thomson, and Judith B. Bruckner. Mathematical Discovery. 2011. http://classicalrealanalysis.info/com/Mathematical-Discovery.php
Cherney, David, et al. Linear Algebra. UC Davis, 2013. https://www.math.ucdavis.edu/~linear
Doerr, Alan, and Kenneth Levasseur. Applied Discrete Structures. 3rd ed. https://faculty.uml.edu/klevasseur/ads2
Fischer, Lane, et al. “A Multi-institutional Study of the Impact of Open Textbook Adoption on the Learning Outcomes of Post-Secondary Students.” Journal of Computing in Higher Education. v.27, no.159 (2015): 159–72.
Goodman, Frederick M. Algebra: Abstract and Concrete. University of Iowa, 2014. https://homepage.divms.uiowa.edu/~goodman
Greenberg, Marvin J. Euclidean and Non-Euclidean Geometries: Development and History. 4th ed., W. H. Freeman and Company, 2008.
Guichard, David. Community Calculus. 2017. https://communitycalculus.org
Hammack, Richard. Book of Proof. 2nd ed. Virginia Commonwealth University, 2013. https://www.people.vcu.edu/~rhammack/BookOfProof
Hartman, Gregory. APEX Calculus. 2015. http://www.apexcalculus.com
Hatcher, Allen. Algebraic Topology. Cambridge, 2002. https://www.math.cornell.edu/~hatcher (CH, Oct’02, 40-0958).
Hefferon, Jim. Linear Algebra. 3rd ed. http://joshua.smcvt.edu/linearalgebra
Hitchman, Michael P. Geometry with an Introduction to Cosmic Topology. 2018. [Originally published by Jones and Bartlett, 2009.] http://mphitchman.com
Inigo, Maxie, et al. College Mathematics for Everyday Life. 2nd ed. Coconino Community College, 2016. https://www.coconino.edu/open-source-textbooks
Judson, Tom. Abstract Algebra: Theory and Applications. 2017. http://abstract.ups.edu
Keller, Mitchel T., and William T. Trotter. Applied Combinatorics. 2017. https://www.rellek.net/appcomb
Leary, Christopher C., and Lars Kristiansen. A Friendly Introduction to Mathematical Logic. 2nd ed. SUNY Geneseo, 2015. https://minerva.geneseo.edu/a-friendly-introduction-to-mathematical-logic
Lebl, Jiří. Basic Analysis: Introduction to Real Analysis. 2016. http://www.jirka.org/ra
__________. Notes on Diffy Qs: Differential Equations for Engineers. 2018. http://www.jirka.org/diffyqs
Levin, Oscar. Discrete Mathematics: An Open Introduction. 2nd ed., 2017. http://discrete.openmathbooks.org/home.php
Lippman, David, and Melonie Rasmussen. Precalculus: An Investigation of Functions. 2nd ed., 2017. http://www.opentextbookstore.com/precalc
Lippman, David. Math in Society. Washington State Community Colleges, 2017. http://www.opentextbookstore.com/mathinsociety/index.html
MERLOT. California State University. https://www.merlot.org (CH, May’14, 51-4799)
MIT Open Courseware. Massachusetts Institute of Technology. https://ocw.mit.edu
Open Textbook Initiative. American Institute of Mathematics. Accessed March 20, 2018. https://aimath.org/textbooks
Open Textbook Library. University of Minnesota Center for Open Education. http://open.umn.edu/opentextbooks
Open UBC. University of British Columbia. https://open.ubc.ca
OpenStax. Rice University. https://openstax.org
Petrunin, Anton. Euclidean Plane and Its Relatives: A Minimalist Introduction. 2018. https://anton-petrunin.github.io/birkhoff
PreTeXt. Open Oregon Educational Resources. https://mathbook.pugetsound.edu
Shoup, Victor. A Computational Introduction to Number Theory and Algebra. 2nd ed. Cambridge University Press, 2008. http://shoup.net/ntb (CH, Jul’06, 43-6576).
Stein, William. Elementary Number Theory: Primes, Congruences, and Secrets. Updated ed., 2017. 1st ed., Springer-Verlag, 2008. https://wstein.org/ent (CH, Oct’09, 47-0925).
Stitz, Carl and Jeff Zeager. College Algebra. 2013. http://www.stitz-zeager.com
Sundstrom, Ted. Mathematical Reasoning: Writing and Proof. Grand Valley State University, 2014. https://www.tedsundstrom.com/mathreasoning [Originally published by Prentice Hall, 2002]. (CH, May’03, 40-5255)
Thomson, Brian S., Judith B. Bruckner, and Andrew M. Bruckner. Elementary Real Analysis. 2nd ed, 2008. [Originally published by Prentice Hall, 2001.] http://www.classicalrealanalysis.info/com/Elementary-Real-Analysis.php
Treil, Sergei. Linear Algebra Done Wrong. 2017. https://www.math.brown.edu/~treil/papers/LADW
Trench, William F. Elementary Differential Equations. Trinity University Faculty Authored Books, 2013. [Originally published by Brooks/Cole, 2001.] https://digitalcommons.trinity.edu/mono/8
__________. Introduction to Real Analysis. Trinity University Faculty Authored Books, 2013. [Originally published by Prentice Hall, 2002.] https://digitalcommons.trinity.edu/mono/7
Wiggins, Stephen. Ordinary Differential Equations. 2017. https://figshare.com/articles/Ordinary_Differential_Equations/5311612
Yoshiwara, Katherine. Modeling, Functions, and Graphs: Algebra for College Students. 2018. https://yoshiwarabooks.org
Zakon, Elias. Mathematical Analysis I. The Trillia Group, 2004. http://www.trillia.com/zakon-analysisI.html