Frustrations over getting Graviga in chatper five

[Milkpea]

I'm doing a complete run through using the Brady guide book but I've come to a point that is totally baffling me. I'm currently in chapter 5 having just got onto the highway where Genesis is attacking the Shinra building. In the book it says to use Graviga on the G Assaliants. I look up where to gain this and it says missions 1-3-5,6-6-2,7-3-6,7-6-6,8-5-6. What's puzzling me is most of these missions ask you to use Graviga on the enemies.
What am I missing? @_@
Thank you

(edit: This is for Crisis core. I forgot to say that in the title)

[Ryu-Kentoshii Hirokima]

This is for FFVII: CC Right?
If it asks you to use Graviga in the missions where you get Graviga...That makes almost no sense, but one of them should be easy, where you don't need to use Graviga to get Graviga...LOL Well, thats all I can tell you right now, If I find out more, than I will let you know about it later.

[Milkpea]

Someone mentioned gaining it through materia fusion of Thundaga and Drain but these are gained after the Graviga mission XD

It's all so very confusing

[the_savior21]

you can just use gravity its pretty much the same just weaker

[Kyreaan]

*possible spoiler*

I would suggest keeping at least one Graviga as soon as you can find one. Once you get to certain missions, it gets very handy with monsters with high VIT and SPR. Having Dualcast with Graviga works very well together as I've also noticed Graviga itself is faster for you than it is casted by monsters.

The part that ticked me off a little is that certain boss monsters are inately guarded by it. This is without Null Magic.