上文的馬可孛羅美洲地图来自美国国会图书馆。搜索图书馆的地图网站，有一段叙述，认为馬可孛羅的美洲地图可能是伪造的。其实馬可孛羅的地图不是伪造，是传抄来自中国的地图。有些引文是来自MapHist（地图历史网），就是我前面提到的明年要关闭的网站。美国国会图书馆针对伪造地图有专页：

http://www.maphistory.info/fakesnotes.html#chinese

列出的伪造地图里包括Ortelius1570世界地图，即被认为利玛窦绘制《坤舆万国全图》的主要参考。而指出伪造地图的文章，很多出自要关闭的MapHist网，现在从美国国会图书馆这网页的链接，指向MapHist的文章，已经不存在。该网站是西方地图学历史的权威网站，参与者是西方地图学的重要人物，建站的是西方地图学中心--荷兰，美国国会图书馆引用很多它的文章。现在漏洞越来越多，真假难分，越弄越糊涂了，无法逐一修改，只好关闭。假如他们的学说真是正确、经典的话，该网站是不会关闭的。

该网站是西方地图学历史的权威网站，参与者是西方地图学的重要人物，建站的是西方地图学中心--荷兰，美国国会图书馆引用很多它的文章。

对西方地图学和有关地理历史考证，不能随便相信。这也是我说的，以西方为中心的地理大发现历史观，随着地图学的漏洞，在《坤舆万国全图解密》出版后，将受到严重挑战。

長期以來，西方地图学的假设中国没有参与，是西方发明地图学，带来中国。但是所有的欧洲绘的地图均存在重大疑点，就是出现200年后欧洲人才知道的地理，完全无法解释。《坤舆万国全图》证明是1430年代明代的作品，解决了所有问题，是西方抄袭了中国的地图。有些是中国地图翻译成欧洲文字，变成西方的作品，例如卫匡国的《中国新地图集》。明清两朝更换之际的混乱，造成大量中国文献流失，使中国人也以为地图学是西方的科技。这个严重错误必须更正。

这是极其重大的科学新闻，也是中外交通史翻案的重大新闻。

以下为美国国会图书馆的网页，关于馬可孛羅地图的一段。John Hessler 是 地图学的权威。

Rossi Map Collection

( MapHist references added January 2009 & October 2011)

Comprising five maps, of which the best known is a small map of Northeast Asia (known as the'Map with Ship'). [For brief descriptions of the other maps see Bagrow and Olshin.]

The 'Map with Ship' was donated to the Library of Congress by Marcian F. Rossi (G7800 coll. M3 copy 1, Marcian F. Rossi Collection). The original group comprised about 15 documents, the remainder of which are now with a private collector in Texas. They were first noted in 1933, according to Bagrow.

The maps are in Latin and Italian, with some Chinese ideograms, and some 'characters resembling Arabic'. No conclusive results have yet been published of any scientific or palaeographical tests, but John Hessler is sharing his initial findings about the analysis that is currently [January 2009] being undertaken at the Library of Congress.

References:
Did Marco Polo "Discover" America? Maps attributed to the 13th-century traveler sketch what looks like the coast of Alaska (a piece by Ariel Sabar for the Smithsonian Magazine, October 2014). This is a trailer for a book due out in November 2014 from the University of Chicago Press: Benjamin B. Olshin, The Mysteries of the Marco Polo Maps.

John W. Hessler, 'Sketching the Unknown: A Phenomenological and Computational Study of the Rossi "Map With Ship"' (on his blog, Warping History: Mathematical Methods in Historical Cartometry, 31 December 2008 - 'A recent C-14 dating of the vellum yielded two age distributions both after 1475 ... In conclusion we have shown that the Rossi "Map With Ship" has no internal or geometric inconsistencies that would lead us to believe that it was definitively copied from a modern map').
     The question of the nature of the projection on the 'Map with a Ship', if there was one, led to a flurry of messages in January 2009 on MapHist - look for 'Rossi', 'Projections' and 'Projectionless' - though much of this was polemical and not about the map in question.

John W. Hessler, messages to the MapHist list, both with heading 'Cartographic Fakes, Tony Campbell, etc.', on 31 January 2008 and 4 February 2008 [about progress with the scientific testing of the maps, to throw light on their date(s) and to retrieve unreadable sections].

Gunnar Thompson, one from a series of messages to the MapHist list from January 2008 onwards, in this case on 4 February 2008, discussing, under the section 'Dating the Map With Ship', his earlier efforts to obtain a radiocarbon dating. [To get round the lack of word-wrapping, paste the text into another document.] On 25 September 2011 Gunnar Thompson returned to the issue, asserting the authenticity of this group of maps, in a message: 'Marco Polo New World Maps--Authentic'. See also two follow-up messages under the heading: 'Brief Comment Concerning: [MapHist] Marco Polo New World Maps--Authentic'.

Benjamin B. Olshin, 'The Mystery of the ‘Marco Polo’ Maps: An Introduction to a Privately-Held Collection of Cartographic Materials Relating to the Polo Family', Terrae Incognitae, 39 (2007): 1-23

Benjamin B. Olshin, abstract of a paper delivered at the 2006 annual meeting of the Society for the History of Discoveries, 'From Northeast Asia to the Pacific Northwest: "Marco Polo" Maps and Myths'.

Benjamin B. Olshin, message to MapHist on 24 April 2006, 'Gavin Menzies / Gunnar Thompson / "Map with Ship"'.

Leo Bagrow, 'Maps from the Home Archives of the Descendants of a Friend of Marco Polo', Imago Mundi, 5 (1948), pp. 3-13 (reproducing the five maps on a fold-out page preceding the article). [Comment from Bagrow about that article in editorial (p.2) in that same issue that 'he has received conservative opinions from many experts'.] Private subscribers to Imago Mundi, and those with institutional access, can get that article via JSTOR.

Online scan:
Library of Congress, 'American Memory': [Map of the Far East and adjacent Pacific] (also known as 'Map-with-ship'). [A brief description accompanying a JPEG2000 scan enlargeable to high resolution - added 22 February 2008].