8.8.3 Can you answer these questions?

8.8.3.1 draw paraboloid and contour curve

https://tex.stackexchange.com/landing/r/digest?cta=question&id=631898

I want to draw the following graph, especially the contour curve what is black line on the surface of the paraboloid 
my MWE is as follows 
\begin{tikzpicture} 
\begin{axis}[xmin=0, xmax=3, ymin=0, ... 
[contour]
 

asked by Ben https://tex.stackexchange.com/landing/r/digest?cta=user&id=258564 Score of 1

8.8.3.2 Biblatex: How do I include links in the reference list?

https://tex.stackexchange.com/landing/r/digest?cta=question&id=631776

I need some help with my reference list using biblatex. Most papers I read have links to websites included in the reference itself without printing the actual link (see first picture). This makes the ... 
[biblatex] [cross-referencing] [links] [hyperlink]
 

asked by Olle https://tex.stackexchange.com/landing/r/digest?cta=user&id=262429 Score of 1

8.8.3.3 latex beamer set circle template radius

https://tex.stackexchange.com/landing/r/digest?cta=question&id=632039

in my opinion the circle in enumerations/the toc is too small when using the circle template. This is why I looked in the docs and found, one may use [circle]{<radius>} as template (c.f. ... 
[beamer]
 

asked by atticus https://tex.stackexchange.com/landing/r/digest?cta=user&id=206293 Score of 1