I just bought the book "German experimental Artillery in the Civil War in Spain (1936-1939)" by Lucas Molina and Jose Maria Manrique.
After reading it I have raised a few doubts about the accuracy of the information given in this book.
According to information from these authors, to Spain arrived one 10.5cm leFH18 howitzer battery, another battery of 15cm sFH18 howitzers and finally one battery of 10.5cm K18 guns. It is assumed that each battery should have 4 pieces, as this was the normal number in each artillery battery of this type in Germany at that time.
However, the analysis of the pictures that illustrate the book provokes thought in other quantities.
As to 10.5cm leFH18:
The photo illustrates the cover of the book clearly shows a battery of four of these howitzers in his motorized version, equipped with metal wheels with solid tyres (It is curious that the Germans be sent to Spain this version).
However, in the photos that appear on pages 8 and 9 of the book, you can clearly see at least 3 of these 10.5cm leFH18 howitzers (with their limbers) but the horse-drawn version, which had a kind of wheels different and lacked rubber tires.
This suggests that perhaps Spain should receive two 10.5cm leFH18 batteries, one of the motorized version and another of the horse-drawn version.
See images 1-2
Besides, on page 2 of the book there is a photo of one of the howitzers of the motorized version towed (by horses) using a standard limber but also equipped with solid tyres. I've never seen one of these limbers (normally only used in towing the horse version) equipped with solid tires.


See image 3
As to 15cm sFH18 :
For the images seems that to Spain were to send howitzers of the horse-drawn version, equipped with wheels without tires and transported in two separate loads using the corresponding limbers.
However, on page 24 there is a photo of the Victory Parade of 1939, in which there are two howitzers 15cm sFH18 but the motorized version, equipped with solid tires and transported on a single charge. (Although in the picture is used strangely the limber of horse-drawn version, which would not be very appropriate)
This suggests that may also receive one mot. version battery or maybe the battery would have received a mix of motorized and horse-drawn howitzers.

Thanks in advance and greetings