deletions | additions       diff --git a/Introduction_Rocks_are_the_primary__.md b/Introduction_Rocks_are_the_primary__.md  index b524df0..1719272 100644  --- a/Introduction_Rocks_are_the_primary__.md  +++ b/Introduction_Rocks_are_the_primary__.md 
...
The vast amounts of nutrients locked in soil minerals has triggered, nearly 100 years ago, the question if plants can actively enter this potential nutrient source \citep{HALEY_1923,TURK_1919}.   Five decades later, studies appear on the role of microorganisms, including mycorrhizal fungi, in mineral weathering \citep{WEBLEY_1963,DUFF_1963,Sperber_1958,Boyle_1967,Boyle_1973}.   More recently, a publication with the provocative title *Rock `Rock  eating fungi* fungi'  appeared in Nature \citep{Jongmans_1997}. This publication presented evidence of, presumably mycorrhizal, fungal hyphae drilling their way (chemically and/or physically) into feldspar grains.   This paper initiated renewed interest into the topic.   A series of reviews has been published since then, covering the research up to 2009 \citep{Finlay_2009,Hoffland_2004,Landeweert_2001}.