Jean Berstel & Michel Pocchiola (1993):
A geometric proof of the enumeration formula for Sturmian words.
Internat. J. Algebra Comput. 3(3),
pp. 349–355,
doi:10.1142/S0218196793000238.
J. Cassaigne, P. Hubert & S. Troubetzkoy (2002):
Complexity and growth for polygonal billiards.
Ann. Inst. Fourier (Grenoble) 52(3),
pp. 835–847.
Available at http://aif.cedram.org/item?id=AIF_2002__52_3_835_0.
E. P. Lipatov (1982):
A classification of binary collections and properties of homogeneity classes.
Problemy Kibernet. 39,
pp. 67–84.
M. Lothaire (2002):
Algebraic combinatorics on words.
Encyclopedia of Mathematics and its Applications 90.
Cambridge University Press,
Cambridge.
Chapter 3, Sturmian Words (by Jean Berstel and Patrice Séébold).
Filippo Mignosi (1991):
On the number of factors of Sturmian words.
Theoret. Comput. Sci. 82(1, Algorithms Automat. Complexity Games),
pp. 71–84,
doi:10.1016/0304-3975(91)90172-X.
Thierry Monteil (2011):
Another Definition for Digital Tangents.
In: DGCI,
Lecture Notes in Computer Science 6607,
pp. 95–103,
doi:10.1007/978-3-642-19867-0_8.
N. Pytheas Fogg (2002):
Substitutions in dynamics, arithmetics and combinatorics.
Lecture Notes in Mathematics 1794.
Springer-Verlag,
Berlin,
doi:10.1007/b13861.
Chapter 6, Sturmian Sequences (by Pierre Arnoux).