Clifford D. Simak book All Flesh is Grass
Source: All Flesh is Grass (1965), Chapter 11 (p. 105)
Clifford Donald Simak was an American science fiction writer. He won three Hugo Awards and one Nebula Award. The Science Fiction Writers of America made him its third SFWA Grand Master, and the Horror Writers Association made him one of three inaugural winners of the Bram Stoker Award for Lifetime Achievement. Wikipedia

Clifford D. Simak book All Flesh is Grass
Source: All Flesh is Grass (1965), Chapter 11 (p. 105)
Clifford D. Simak book Time is the Simplest Thing
Source: Time is the Simplest Thing (1961), Chapter 9 (p. 70)
Clifford D. Simak Highway of Eternity
Highway of Eternity (1986)
Clifford D. Simak book City
Notes on the Fifth Tale (p. 119)
City (1952)
“Beyond his own sure knowledge, he had not a shred of proof.”
“The Sitters” (p. 90)
Short Fiction, Skirmish (1977)
“These are the stories the Dogs tell, when the fires burn high and the wind is from the north.”
Clifford D. Simak book City
Editor’s Preface (p. 5)
City (1952)
Clifford D. Simak book Time and Again
Source: Time and Again (1951), Chapter XII (p. 72)
Clifford D. Simak book Way Station
Source: Way Station (1963), Ch. 19
Clifford D. Simak book City
Source: City (1952), Chapter 7, “Aesop” (p. 210)
Clifford D. Simak book City
Source: City (1952), Chapter 7, “Aesop” (pp. 195-196)
Clifford D. Simak book Time is the Simplest Thing
Source: Time is the Simplest Thing (1961), Chapter 3 (p. 14)
Clifford D. Simak book City
Source: City (1952), Chapter 7, “Aesop” (p. 207)
Clifford D. Simak book City
Notes on the First Tale (pp. 9-10)
City (1952)
“They’re just ordinary people,” Nancy said. “You can’t expect too much of them.”
Clifford D. Simak book All Flesh is Grass
Source: All Flesh is Grass (1965), Chapter 17 (p. 179)
Clifford D. Simak book Time is the Simplest Thing
Source: Time is the Simplest Thing (1961), Chapter 13 (p. 101)
Clifford D. Simak book Time and Again
Source: Time and Again (1951), Chapter XLII (p. 215)
Clifford D. Simak book Time is the Simplest Thing
Source: Time is the Simplest Thing (1961), Chapter 32 (p. 249)
Clifford D. Simak book City
Notes on the Third Tale (p. 69)
City (1952)
Clifford D. Simak book Time is the Simplest Thing
Source: Time is the Simplest Thing (1961), Chapter 30 (p. 227)
Clifford D. Simak book Time and Again
Source: Time and Again (1951), Chapter XXVIII (p. 143)
Clifford D. Simak book Time is the Simplest Thing
Source: Time is the Simplest Thing (1961), Chapter 32 (p. 245)
Clifford D. Simak book City
Source: City (1952), Chapter 7, “Aesop” (p. 201)
Clifford D. Simak book Way Station
Source: Way Station (1963), Ch. 35
Clifford D. Simak book Time is the Simplest Thing
Source: Time is the Simplest Thing (1961), Chapter 10 (p. 75)
“The Sitters” (p. 73); originally published in Galaxy Science Fiction, April 1958
Short Fiction, Skirmish (1977)
Clifford D. Simak book City
Source: City (1952), Chapter 1, “City” (p. 31)
Clifford D. Simak book Way Station
Source: Way Station (1963), Ch. 15
Clifford D. Simak book City
Source: City (1952), Chapter 5, “Paradise” (p. 139)
Clifford D. Simak book All Flesh is Grass
Source: All Flesh is Grass (1965), Chapter 24 (p. 247)
Clifford D. Simak book City
Source: City (1952), Chapter 7, “Aesop” (pp. 206-207)
Clifford D. Simak book Time and Again
Source: Time and Again (1951), Chapter XXV (p. 134)
Clifford D. Simak book Way Station
Source: Way Station (1963), Ch. 21
Clifford D. Simak book All Flesh is Grass
Source: All Flesh is Grass (1965), Chapter 18 (p. 195)
Clifford D. Simak book All Flesh is Grass
Source: All Flesh is Grass (1965), Chapter 17 (p. 179)
Clifford D. Simak book Way Station
Source: Way Station (1963), Ch. 30
“The Thing in the Stone” (pp. 211-212); originally published in Worlds of If, March 1970
Short Fiction, Skirmish (1977)
“The Big Front Yard” (pp. 142-143); originally published in Astounding Science Fiction, October 1958
Short Fiction, Skirmish (1977)
Clifford D. Simak book Time and Again
Source: Time and Again (1951), Chapter XXV (p. 135)
Clifford D. Simak book Time and Again
Source: Time and Again (1951), Chapter XXXIX (p. 195)
Clifford D. Simak book Time is the Simplest Thing
Source: Time is the Simplest Thing (1961), Chapter 26 (p. 206)
Clifford D. Simak book Time and Again
Source: Time and Again (1951), Chapter XXIV (p. 124)
“Before Man goes to the stars he should learn how to live on Earth.”
Clifford D. Simak book Time and Again
Source: Time and Again (1951), Chapter XLI (p. 204)
“It wouldn’t be the truth,” said Sutton.
“That,” said Trevor, “doesn’t have a thing to do with it.”
Clifford D. Simak book Time and Again
Source: Time and Again (1951), Chapter XLII (p. 220)
Clifford D. Simak book Time is the Simplest Thing
Source: Time is the Simplest Thing (1961), Chapter 5 (p. 26)
“They are worse than the disinherited. They are not the has-beens, they are the never-weres.”
Clifford D. Simak book Time and Again
Source: Time and Again (1951), Chapter II (p. 14)
Clifford D. Simak book Time and Again
Source: Time and Again (1951), Chapter XXI (p. 107)
“The old and the young, he thought. The old, who do not care; the young, who do not think.”
“The Autumn Land” (p. 250); originally published in The Magazine of Fantasy and Science Fiction, October 1971
Short Fiction, Skirmish (1977)