Lead medal, which sources are meant here in "Medallic illustrations 2" p.23 ?

Recently I acquired a lead medal which turned out to be mentioned in “Medallic illustrations of the history of Great Britain and Ireland to the death of George II , part 2” on page 23. The description is as follows: 

“191. William III. and Louis XIV. contrasted. April, 1691. Louis XIV., as a Roman Emperor, leans decrepitly upon a sword with a blade consisting of coins, the point resting upon an exploding bomb. Above are lightnings and in the back- ; ground mons in flames, and Louis's state coach followed by some court ladies. Leg. unam sic occupat urbem. (Thus . . . he seizes one city.) Ex. ludovicus . xiiii . oppressor . decrepitus. (Louis XIV., the decrepit Oppressor.) Rev. William III., as a Roman Emperor, holds a standard decorated with the Christian monogram and the cap of Liberty, and resting on a globe in his other hand is a drawn sword ; above are rays from heaven on one side is a trophy of the ; crowned shields and flags of the United Kingdoms on the ; other, terrified harpies fleeing away. Leg. his armis . tria regna parat. (By these arms he obtains three kingdoms.) . Ex. guilelmus in liberator florens. (William III., the . . successful Liberator.) 2-05. Van Loon, IV. 46. MB. M. Hague, M. P. H. Van Gelder, lead. Gotha, M. Very rare. This medal draws a contrast between the two kings. Louis is represented as a decrepit oppressor, leaning upon the emblems of bribery and cruelty, by which he was supposed to have obtained possession of Mons, whence he is seen returning to Versailles accompanied by the ladies of his court. William appears as a successful protector of religion and liberty, expelling the Harpies of Discord from the British Isles.”

I am happy to see confirmed here that indeed there exists a lead version of this medal, as in my search for identification I already had found the silver one in the British Museum, with the obverse and reverse having their own page, respectively at: https://www.bmimages.com/preview.asp?image=01613138032&itemw=4&itemf=0001&itemstep=1&itemx=4 and at https://www.bmimages.com/preview.asp?image=01613138031&itemw=4&itemf=0001&itemstep=1&itemx=5 . 

Now that I know that I am curious for more information on the medal and in the description in  Medallic illustrations 2 there is this sentence mentioning other sources, at least it seems so to me. The sentence: “2-05. Van Loon, IV. 46. MB. M. Hague, M. P. H. Van Gelder, lead. Gotha, M. Very rare. "

Here are mentioned: 

• Van Loon, IV. 46
• MB. M. Hague
• M. P. H. Van Gelder, lead
• Gotha, M.

I am not sure if these sources sound familiar to anybody on this forum, but any help is very welcome.

In the meantime I found out that the mentioned sources probably point to respectively:

[Van Loon, IV. 46] → "HISTOIRE METALLIQUE DES XVII PROVINCES DES PAYS - BAS. TOME QUATRIEME", a pdf of this book can be found here. (The other volumes of that book series are easily retrieved by changing the number “4” in the URL into the desired volume number.) B.t.w here at Numista there is also a link to this volume, but that is not the complete pdf, it is on Google books.

[MB.] ‘British Museum’ 

[M. Hague] stands for ‘Museum The Hague’, by which is most probably meant “Het Koninklijk Penning Kabinet”, which was part of “Het Rijksmuseum”, but ceased to exist and now that collection can be found at “De Nieuwe Schatkamer” of DNB (De Nederlandse Bank), which is part of the central bank of The Netherlands.  I searched their database NUMIS (https://www.denieuweschatkamer.nl/geldcollectie/munten-vinden-reinigen-en-laten-onderzoeken/numis/?p=1&l=15), but I got no hits there.

[M. P. H. Van Gelder, lead] I am not sure if the letter “M” here is part of the name or means ‘museum’ too. I guess it is part of the name, because no Museum of that name can be found. I contacted De Nieuwe Schatkamer for information and I hope they know more.

[Gotha, M.] means Museum in Gotha, Germany (Ducal Museum Gotha, part of Stiftung Friedenstein Gotha, with historic numismatic holdings).
The collection includes 17th-century medals. I couls inquire via stiftung-friedenstein.de or their numismatic library for access, but as I am looking for the lead version, this has no priority for me.