Mihova V, Ninova J. DIRECT AND INDIRECT METHODS OF PROOF. THE LEHMUS-STEINER THEOREM. Ann. Sofia Univ. Fac. Math. and Inf. [Internet]. 2016 Dec. 12 [cited 2024 Dec. 4];103:105-21. Available from: https://stipendii.uni-sofia.bg/index.php/fmi/article/view/59