Johan Christian Dahl. Letter to Dresden Gëmaldegalerie. September 26, 1840 [published in Christie's sale cat., October 7, 1999, p. 19], remarks that Friedrich made several copies of the Dresden picture.
Werner Sumowski. Caspar David Friedrich-Studien. Wiesbaden, 1970, p. 179, fig. 395, mentions it as a replica of the Dresden picture; as in a private collection of a family in Wuppertal-Barmen to whose ancestor, Fritz von Rosenberg, Friedrich gave it.
Helmut Börsch-Supan and Karl Wilhelm Jähnig. Caspar David Friedrich: Gemälde, Druckgraphik und bildmässige Zeichnungen. Munich, 1973, pp. 356, 415–16, no. 366, ill. (color), as "Zwei Manner in Betrachtung des Mondes" in a private collection at Wuppertal-Barmen.
Hans-Werner Grohn in Werner Hofmann. Caspar David Friedrich, 1774–1840. Exh. cat., Hamburger Kunsthalle. Munich, 1974, p. 227.
Helmut Börsch-Supan. L'opera completa di Friedrich. Milan, 1976, p. 105, no. 182, ill., calls it "Due uomini davanti alla luna" and dates it about 1829; as in a private collection in Wuppertal-Barmen; states that, according to family tradition, Friedrich gave it to his doctor Fritz von Rosenberg.
John Leighton in Caspar David Friedrich: Winter Landscape. Exh. cat., National Gallery. London, 1990, pp. 41, 70 [German ed., "Caspar David Friedrich: Winterlandschaften," (Heidelberg), 1990, pp. 136, 138, no. 37, ill. (color)].
Gary Tinterow and Sabine Rewald in "Recent Acquisitions, A Selection: 1999–2000." Metropolitan Museum of Art Bulletin 58 (Fall 2000), p. 36, ill. (color), call it the second of three works on this theme and note that in this version Friedrich is thought to have painted it in remembrance of his favorite student, August Heinrich, who had died recently; remark that the images of the fir, gnarled oak, and rising moon are subject to interpretation.
Sabine Rewald. Caspar David Friedrich: Moonwatchers. Exh. cat., The Metropolitan Museum of Art. New York, 2001, pp. 7, 18–19, 31, 33–35, no. 3, ill. (color, overall and detail on cover), calls it "Two Men Contemplating the Moon (Zwei Männer in Betrachtung des Mondes)," dates it about 1830, one of two versions Friedrich painted of the work in Dresden and the one more like the original; remarks that it retains the luminosity of the Berlin version, yet reintroduces the complicity between the figures of the Dresden painting; notes that there is no underdrawing.
Roberta Smith. "The Primly Austere, and Occasionally Dark Side of the Moon." New York Times (September 14, 2001), p. E30, ill.
Philippe de Montebello in Sabine Rewald. Caspar David Friedrich: Moonwatchers. Exh. cat., The Metropolitan Museum of Art. New York, 2001, p. 6.
Kasper Monrad in Sabine Rewald. Caspar David Friedrich: Moonwatchers. Exh. cat., The Metropolitan Museum of Art. New York, 2001, pp. 23, 27.
Sabine Rewald in The Wrightsman Pictures. New York, 2005, pp. 342–45, no. 96, ill. (color).
Sabine Rewald in Masterpieces of European Painting, 1800–1920, in The Metropolitan Museum of Art. New York, 2007, pp. 17, 249, no. 15, ill. (color and black and white).