J. C. Birget, Concatenation of inputs in a two-way automaton, Theor. Comput. Sci, vol.63, issue.2, pp.90075-90078, 1989.

V. Carnino and S. Lombardy, On Determinism and Unambiguity of Weighted Two-way Automata, AFL'14. EPTCS, vol.151, pp.188-200, 2014.
URL : https://hal.archives-ouvertes.fr/hal-01326283

J. Engelfriet and H. J. Hoogeboom, MSO definable string transductions and two-way finite-state transducers, ACM Trans. Comput. Log, vol.2, issue.2, pp.216-254, 2001.

H. Leung, Limitedness theorem on finite automata with distance functions: an algebraic proof, Theoret. Comp. Sci, vol.81, issue.1, pp.137-145, 1991.

S. Lombardy, Weighted two-way automata, NCMA'15. books@ocg.at, vol.318, pp.37-47, 2015.
URL : https://hal.archives-ouvertes.fr/hal-01187754

M. O. Rabin and D. Scott, Finite automata and their decision problems, IBM J. Res. Dev, vol.3, issue.2, pp.114-125, 1959.

J. C. Shepherdson, The reduction of two-way automata to one-way automata, IBM J. Res. Dev, vol.3, issue.2, pp.198-200, 1959.