The Soyuz 4

Soyuz 4 launched January 14, 1969. On board was the cosmonaut Vladimir Shatalov on his first flight. The aim of the mission was to dock with Soyuz 5, transfer two crew members from that spacecraft and reenter. The last three Soyuz flights had attempted to do this but had all failed for various reasons.
The radio callsign of the crew was "Amur"; that of Soyuz 5, with which it was to dock, was "Baikal". This referred to the trans-Siberian railway project called the Baikal-Amur Mainline, which was under construction at the time. Hence the docking served as encouragement to the
workers on that project.

Salyut 4 (DOS-4) (Russian: Салют-4; English translation: Salute 4) was launched on December 26, 1974. It was essentially a copy of the DOS-3, and unlike its ill-fated sibling it was a complete success. Three crews made stays aboard Salyut 4 (Soyuz 17, Soyuz 18 and Soyuz 21), including one of 63 days duration, and an unmanned Soyuz capsule remained docked to the station for three months, proving the systems' long-term durability. Salyut 4 was deorbited February 2, 1977, and re-entered the Earth's atmosphere on February 3.