The paper discusses the problem of finding quantum-error-correcting codes by transforming it into the problem of constructing additive codes over the field GF(4) that are self-orthogonal with respect to a specific trace inner product. The authors present many new codes and bounds, and provide a table of upper and lower bounds on such codes up to 30 qubits. The paper is structured into several sections, covering the introduction, the transformation of quantum codes to binary spaces, the relationship between isotropic spaces and codes over GF(4), general constructions, cyclic and related codes, and self-dual codes. The authors also discuss the Clifford groups and their role in encoding and decoding quantum codes. The paper concludes with an update on recent developments in the field.The paper discusses the problem of finding quantum-error-correcting codes by transforming it into the problem of constructing additive codes over the field GF(4) that are self-orthogonal with respect to a specific trace inner product. The authors present many new codes and bounds, and provide a table of upper and lower bounds on such codes up to 30 qubits. The paper is structured into several sections, covering the introduction, the transformation of quantum codes to binary spaces, the relationship between isotropic spaces and codes over GF(4), general constructions, cyclic and related codes, and self-dual codes. The authors also discuss the Clifford groups and their role in encoding and decoding quantum codes. The paper concludes with an update on recent developments in the field.