What is it called when you make a reference in the text of a document alerting the reader that you are using information from another source?

Pseudocode pld #6, pg. 117 start// declarations// number numbertoguess// number myguess; numbertoguess = 92// while myguess ! = numbertoguess// output " guess an integer number between 1 and 100"// input myguess// if (myguess == numbertoguess)// output "you guessed the correct number"// else// output "the number you guessed was incorrect. try again! "// end if// end while// output " for playing the guessing game. have a great day! "// stop