[NH<sub>2</sub>NH<sub>3</sub>][M(HCOO)<sub>3</sub>] (M = Mn<sup>2+</sup>, Zn<sup>2+</sup>, Co<sup>2+</sup>and Mg<sup>2+</sup>): structural phase transitions, prominent dielectric anomalies and negative thermal expansion, and magnetic ordering
Distribution of the number of citations over years.