This circuit is from a technical documentation from the 70s. It makes use of married transistors in a single enclosure, which are not easy to obtain today. Common transistors with equal gains (matched pairs) can be used. The operational can also be of a more modern type. The circuit has a zero-setting, and, in addition, it must be powered by a symmetrical source. The input impedance is too high. The LM113 is a voltage regulator from National Semiconductor, also not very easy to obtain today.
