Original sentence: During this time, he found it so difficult to find good writers to contribute to the magazine, that he often wrote most of the stories himself under a variety of pseudonymns: one issue of Authentic (issue 68, April 1956) was written entirely by Tubb, including the letters column.The Dying Tree (2000), as by Edward Thomson (reprint of Drums of the Prarie [1956])
Edited sentence: During this time, he found it so difficult to find good writers to contribute to the magazine, that he often wrote most of the stories himself under a variety of pseudonyms: one issue of Authentic (issue 68, April 1956) was written entirely by Tubb, including the letters column.The Dying Tree (2000), as by Edward Thomson (reprint of Drums of the Prairie [1956])