1. Solution of systems of equations in one unknown in free groups;Lorenc, A. A.;Dokl. Akad. Nauk SSSR,1963
2. Coefficient-free equations in free groups;Lorenc, A. A.;Dokl. Akad. Nauk SSSR,1965
3. Equations in free groups;Lyndon, Roger C.;Trans. Amer. Math. Soc.,1960
4. The equation 𝑎^{𝑀}=𝑏^{𝑁}𝑐^{𝑃} in a free group;Lyndon, R. C.;Michigan Math. J.,1962