fix links

docs/modules/core/pages/material/how_to_use_materials.adoc

@@ -10,7 +10,7 @@ A Geometry (mesh) is just the shape of the object. jMonkeyEngine cannot render a
 *  Each Material is based on a Material Definition file. +
 Examples of included Material Definitions: Lighting.j3md, Unshaded.j3md
 
-You want to make the most of your 3D models by specifying good looking material parameters. The developers must be in contact with the graphic designers regarding which of the xref:material/materials_overview.adoc[Material properties] they intend to use in their 3D models. You must have an understanding what <<intermediate/terminology.adoc#materials-textures,texture maps>> are, to be able to use texture-mapped materials.
+You want to make the most of your 3D models by specifying good looking material parameters. The developers must be in contact with the graphic designers regarding which of the xref:material/materials_overview.adoc[Material properties] they intend to use in their 3D models. You must have an understanding what <<tutorials:concepts/terminology.adoc#materials-textures,texture maps>> are, to be able to use texture-mapped materials.
 
 
 [IMPORTANT]

docs/modules/tutorials/pages/concepts/math.adoc

@@ -2,7 +2,7 @@
 :revnumber: 2.1
 :revdate: 2020/07/24
 
-It's a fact of life, math is hard. Unfortunately, 3D graphics require a fair bit of knowledge about the subject. Fortunately, jME is able to hide the majority of the details away from the user. Vectors are the fundamental type in the 3D environment, and it is used extensively. Matrices are also a basic necessity of 3D for representing linear systems. xref:xref:core:math/quaternion.adoc[Quaternions] are perhaps the most powerful and complicated of the basic types and are used for rotation in jME.
+It's a fact of life, math is hard. Unfortunately, 3D graphics require a fair bit of knowledge about the subject. Fortunately, jME is able to hide the majority of the details away from the user. Vectors are the fundamental type in the 3D environment, and it is used extensively. Matrices are also a basic necessity of 3D for representing linear systems. xref:core:math/quaternion.adoc[Quaternions] are perhaps the most powerful and complicated of the basic types and are used for rotation in jME.
 
 I'll discuss how these are used in the system for the core functionality. Including Transforming, Visibility Determination, Collision Detection, and the Coordinate System. Note, that these are low level details. Further chapters will discuss how to use these various systems from a high level perspective.
 
@@ -749,7 +749,7 @@ A triangle is a 3-sided polygon. Every triangle has three sides and three angles
 
 === Usage
 
-jME's Triangle class is a simple data class. It contains three <<intermediate/terminology.adoc#vectors,Vector3f>> objects that represent the three points of the triangle. These can be retrieved via the `get` method. The `get` method, obtains the point based on the index provided. Similarly, the values can be set via the `set` method.
+jME's Triangle class is a simple data class. It contains three <<concepts/terminology.adoc#vectors,Vector3f>> objects that represent the three points of the triangle. These can be retrieved via the `get` method. The `get` method, obtains the point based on the index provided. Similarly, the values can be set via the `set` method.
 
 
 === Example 1 - Creating a Triangle

docs/modules/tutorials/pages/how-to/debugging.adoc

@@ -297,4 +297,4 @@ getViewPort().addProcessor(new WireProcessor());
 
 == See also
 
-*  xref:scene/spatial.adoc[Spatial] – if you can't see certain spatials, you can modify the culling behaviour to identify problems (such as inside-out custom meshes)
+*  xref:core:scene/spatial.adoc[Spatial] – if you can't see certain spatials, you can modify the culling behaviour to identify problems (such as inside-out custom meshes)