Peregrinations along Magic Trails and Places is a travelogue authored by Buyvid Backhuysen describing, among others, Tor Zireael.
Excerpt
We trekked perhaps four hundred furlongs southwards from the ancient and far-famed city of Assengard, to a land called Centloch. When one looks on that land from the hills, one sees numerous lakes arranged, artificially, in manifold dispositions. Our guide, the elf Avallac'h, ordered us to seek among those dispositions one calling to mind a cloverleaf. And, in truth, we espied one such. Moreover, it came out that there were not three but four lakes, for one, somewhat elongated, stretching from south to north, is, as it were, the stem of the leaf. That lake, known as Tarn Mira, is ringed by a black forest. Meanwhile, the mysterious Tower of the Swallow, in the elven tongue Tor Zireael, was said to rise up at its northern margin. At first, nonetheless, we saw nothing save fog. I was readying myself to ask the elf Avallac'h about the tower, when he gestured me to be silent and spoke these words: "Await and hope. Hope shall return with the light and good omen. Gaze at the endless waters; there you shall discern the envoys of good tidings."
pg. 301, The Tower of the Swallow (UK edition)
Name of the book is translated as Peregrinations Among Magic Paths and Places and is placed in Traveler's diary, a quest item.