How many spectres in a build?

Hi just new to the game and following a ghazzy spectre build I found on google. I was curious how many spectres can be up for example at once? I have 4 up and running right now but is there room for more? Is there a list in the threads somewhere of how to get +1 spectre stuff?

Also curious about another popular spectre build just so I can compare with what I'm doing? THnx for the read. On a side note, I guess the same could be asked about zombies as I have 6 up running around. So I would like to maximize spectres and zombies helping me out.

The Path of Exile Gamepedia say you can have 8 Spectres with specific uniques

https://pathofexile.gamepedia.com/Raise_Spectre#Total

And 23 Zombies with other uniques.

https://pathofexile.gamepedia.com/Raise_Zombie#Total

Since i'm not a Summoner myself, i can't say if there are good builds out here but Kwitch manage a list of all builds with good results in end-game here

http://www.pathofexile.com/forum/view-thread/1774022

As a Zombie summoner myself, before I get to use Montrgul's Grasp unique which halves your Zombies' total count, I normally have 8-13 running around at any given point. But these Zombies pale in comparison to Montregul Zombies.