Arkady Strugatsky [Russian: Аркадий Стругацкий] and Boris Strugatsky [Russian: Борис Стругацкий]

Space Apprentice (also known as Probationers, includes "The Gigantic Fluctuation" short story). The novel's main character is Yuri Borodin, a young space welder. His mother was sick and Yuri missed the spaceship that was to transport him to his new work site. He gets a ride to his destination on a ship piloted by some of the characters of The Land of Crimson Clouds.

The Way to Amalthea (also known as Destination: Amaltheia). A cargo spaceship, propelled by a photon engine with a large reflective mirror ("sail"), visits the Jupiter system to deliver cargo to a staffed science station on Amalthea. Damaged by meteorites, the spaceship falls into Jupiter, but survives the pressure and floats in the dense atmosphere; the crew manage to work around the damaged mirror and start the main engine to escape Jupiter and finally reach Amalthea.

The Land of Crimson Clouds. A spaceship, propelled by a prototype photon engine, sets off for Venus, which at that time, is an enigmatic and unexplored planet covered by clouds. The tasks of the crew are a) to test the prototype engine in field conditions and b) to locate and set radio beacons on the so called "Uranium Golconda" (a place with incredibly large heavy metals deposits), presumably, found somewhere on the second planet of the Solar System.