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Monster girl encyclopedia, interviews with monster girls, monster girl infirmary,12 beast and any other monster girl manga or anime or game are not related monster musume is its oun thing Monster Musume, Vol. 1 https://www.amazon.com/dp/1937867900/ref=cm_sw_r_cp_apa_bakDBbTW4NM78 heres the link to volume 1 on amazon of monster musume
here's a link to get you started if you like the first chapter I highly suggest picking it up
Pretty sweet, as for recommendations you BADLY need to get monster musume, its the king of echi comedy and my favourite.
As for rosario + vamp they are brining out a boxset near xmas, so dunno if you wanna wait until then to get them all.
Also you should think about getting high school DxD the manga, its pretty simmiler to the anime though so only if your really wanna have it on your shelf in book form.
btw, is Citrus good? I am gonna order it along with this series is as well in a few days
Oh and another good echi comedy with an interesting story and its only 3 vols big - http://www.amazon.co.uk/Love-Hell-Vol-Reiji-Suzumaru/dp/1937867897/ref=sr_1_2?s=books&ie=UTF8&qid=1431742220&sr=1-2&keywords=love+in+hell
I don't see love in hell hardly ever mentioned so I don't know if its just not a very popular manga but its a pretty rare gem worth checking out.
Sorry btw if its too much echi. I just saw rosario + vamp and sora nagihara and thought of these xD I would say dragnor maybe counts as echi but in all honesty it creeps me out, still own 5 of them but still don't stop the naked parts from creeping me out to no end.
PS: Please for the love of god if you read monster musume PM me and tell me what you thought xD