4 http://hdl.handle.net/10338.dmlcz/105029 4 Sum of categories with amalgamated subcategory http://hdl.handle.net/10338.dmlcz/105037 Sum of categories with amalgamated subcategory Freie Erweiterungen von Schemen $n$-ten Grades http://hdl.handle.net/10338.dmlcz/105036 Freie Erweiterungen von Schemen $n$-ten Grades Model $\nabla[\omega_\alpha\to\omega_\beta]$ in which $\beta$ is limit number http://hdl.handle.net/10338.dmlcz/105035 Model $\nabla[\omega_\alpha\to\omega_\beta]$ in which $\beta$ is limit number On finite and countable rigid graphs and tournaments http://hdl.handle.net/10338.dmlcz/105034 On finite and countable rigid graphs and tournaments