The first passage below is Childress:
Rudbeck based his theory of Sweden having been Atlantis by assuming that Plato’s Atlantis was the same as Homer’s Isle of Ogygia. Rudbeck used the sailing directions in the Odyssey to conclude that Ogygia lay between the latitudes of Mecklenberg, Germany and Vinililand, Sweden. Rudbeck felt that the ancient Norse sagas vindicated his identification of Sweden as Atlantis. Its capital had been Uppsala, the very city Rudbeck lived in. (Lost Cities of Atlantis, 1996, p. 333)
The second is L. Sprague de Camp:
He began by assuming that Plato's Atlantis and Homer’s isle of Ogygia were the same. Then, from the scanty and vague sailing-directions in the Odyssey and some remarks by the unscientific Plutarch on the shape of the earth, Rudbeck inferred that Atlantis must have lain between the latitudes of Mecklenberg, Germany and Vinililand, Sweden. By bending the poetry of the Viking Age to his service, he proved to his own satisfaction that Atlantis was Sweden with its capital near Upsala (sic), and was moreover the fountainhead of all civilization. (Lost Continents, 1970 , p. 178)
Notice similarities? While Childress cites de Camp as the source for his passage, it is remarkable just how closely he apes de Camp's language, including the presentation of information and even the word order of each sentence. Specific words--"assuming," "isle" (note this use from de Camp and not "island," as usually translated from Homer), "sailing directions," the whole phrase beginning "between the latitudes...", "its capital"--are all repeated in the same order, following de Camp's sentence structure closely enough to show that the entire passage is dependent upon de Camp. The end note, merely citing de Camp's book in general without page numbers, fails to indicate what material in this passage (all of it) is paraphrasing de Camp, or that it is paraphrased at all. While this is not a simple cut-and-paste job, it is the kind of extremely close paraphrasing with poor or ambiguous citation that has tripped up many scholars.
A quick check of Childress's other books indicates that many passages are closely dependent on other sources in much the same way. Additionally, many passages in his own books seem to be repeated nearly verbatim from book to book. No wonder he can crank them out so fast.
And I'm the crappy scholar.