diff --git a/concepts/derivative.md b/concepts/derivative.md
index e2a3981..da732c5 100644
--- a/concepts/derivative.md
+++ b/concepts/derivative.md
@@ -1,7 +1,9 @@
 # Derivative
-A derivative is a type of financial contract whose value is dependent on an underlying asset, group of assets, or benchmark.
+A derivative is a type of financial contract whose value is dependent on an *underlying* asset, basket of assets, or a benchmark of other assets.
 
-Underlying assets for derivatives are most often stocks, bonds, commodities, currencies, interest rates, and market indexes. The value of the contract itself depend on changes in the prices of the underlying asset.
+Underlying for derivatives are most often [stocks](stock.md), [bonds](bond.md), [commodites](commodity.md), [currencies](currency.md), debt and market indexes. The value of the contract itself depend on changes in the prices of the underlying asset. 
+
+A derivative is a type of [financial asset](financial-asset.md). Derivatives have no [use value](use-value.md). Their [fundamental value](fundamental-value.md) and demand is generated from their the demand of the underlying.
 
 ## Examples
 * Futures
diff --git a/concepts/enclosure.md b/concepts/enclosure.md
new file mode 100644
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+++ b/concepts/enclosure.md
@@ -0,0 +1 @@
+## Enclosure
diff --git a/concepts/financial-asset.md b/concepts/financial-asset.md
new file mode 100644
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+# Financial Asset
+A financial asset is a non-physical asset whose value is derived from a contractual claims on [income cashflows](income-cashflows.md), an underlying [currency](currency.md) or [commodity](commodity.md), or risk transfer between counterparties.
+
+Financial assets definitionally have no [use value](use-value.md).  However a financial asset with must have either income or an underlying that generates its [fundamental-value](fundamental-value.md). 
+
+See also [ficticious commodity](ficticious-commodity.md).
+
+## Examples
+* [Stock](stock.md)
+* [Bond](bond.md)
+* [Credit default swap](cds.md)
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diff --git a/concepts/fundamental-value.md b/concepts/fundamental-value.md
index 6024847..574eecc 100644
--- a/concepts/fundamental-value.md
+++ b/concepts/fundamental-value.md
@@ -1,2 +1,4 @@
 # Fundamental Value
-Fundamental value is the [present-value](present-value.md) of all expected future net [income-cashflows](income-cashflows.md) to the asset calculated via discounted cash flow valuation.
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+Fundamental value is the [present-value](present-value.md) of all expected future net [income-cashflows](income-cashflows.md) to the asset calculated via discounted cash flow valuation.
+
+See also [financial asset](financial-asset.md).
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diff --git a/concepts/howey-test.md b/concepts/howey-test.md
index b25624e..4c99043 100644
--- a/concepts/howey-test.md
+++ b/concepts/howey-test.md
@@ -1,9 +1,9 @@
 # Howey Test
 A legal test which defines whether an investment contract is designed as a [security](security.md) under United States law.
 
-1. Investment of money 
-2. In a common enterprise 
-3. With the expectation of profit 
+1. Investment of money
+2. In a common enterprise
+3. With the expectation of profit
 4. To be derived from the efforts of others
 
 ## References
@@ -11,4 +11,4 @@ A legal test which defines whether an investment contract is designed as a [secu
 1. Burilov, Vlad. 2019. ‘Regulation of Crypto Tokens and Initial Coin Offerings in the EU: De Lege Lata and de Lege Ferenda’. European Journal of Comparative Law and Governance 6 (2): 146–86. https://doi.org/10.1163/22134514-00602003.
 1. Cornish, Chloe, and Richard Waters. 2018. ‘Silicon Valley Investors Line up to Back Telegram ICO’. Financial Times, January. https://www.ft.com/content/790d9506-0175-11e8-9650-9c0ad2d7c5b5.
 1. Hacker, Philipp, and Chris Thomale. 2018. ‘Crypto-Securities Regulation: ICOs, Token Sales and Cryptocurrencies under EU Financial Law’. European Company and Financial Law Review 15 (4): 645–96.
-1. Zetzsche, Dirk A, Ross P Buckley, Douglas W Arner, and Linus Föhr. 2017. ‘The ICO Gold Rush: It’s a Scam, It’s a Bubble, It’s a Super Challenge for Regulators’. University of Luxembourg Law Working Paper, no. 11: 17–83.
+1. Zetzsche, Dirk A, Ross P Buckley, Douglas W Arner, and Linus Föhr. 2017. ‘The ICO Gold Rush: It’s a Scam, It’s a Bubble, It’s a Super Challenge for Regulators’. University of Luxembourg Law Working Paper, no. 11: 17–83.
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diff --git a/concepts/productive-asset.md b/concepts/productive-asset.md
index 5cb007c..0565391 100644
--- a/concepts/productive-asset.md
+++ b/concepts/productive-asset.md
@@ -1,9 +1,13 @@
 # Productive Asset
+Productive assets are [assets](assets.md) which have [income-cashflows](income-cashflows.md) attached to them. Examples include stocks, real estate, and bonds.
 
-Productive assets are [assets](assets.md) which have [income-cashflows](income-cashflows.md)  attached to them. Examples include stocks, real estate, and bonds.
+[Commodities](commodity.md) are non-productive assets.
 
-Commodities are non-productive assets.
+[Art](art.md) is a non-productive asset.
 
-Art is a non-productive assets.
+[Crypto tokens](cryptoasset.md) are non-productive assets.
 
-Crypto tokens are non-productive assets.
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+## References
+* Hanley, Brian P. 2018. ‘The False Premises and Promises of Bitcoin’. ArXiv:1312.2048 [Cs, q-Fin], July. http://arxiv.org/abs/1312.2048.
+1. Taleb, Nassim Nicholas. 2021. ‘Bitcoin, Currencies, and Fragility’. ArXiv:2106.14204 [Physics, q-Fin], July. http://arxiv.org/abs/2106.14204.
+* ‘Why Bitcoin Is Worse than a Madoff-Style Ponzi Scheme | Financial Times’. n.d. Accessed 20 March 2022. https://www.ft.com/content/83a14261-598d-4601-87fc-5dde528b33d0.
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diff --git a/concepts/shadow-bank.md b/concepts/shadow-bank.md
index 1e1cc70..3d2432e 100644
--- a/concepts/shadow-bank.md
+++ b/concepts/shadow-bank.md
@@ -1,4 +1,11 @@
 # Shadow Bank
 A shadow banking system refers to a network of unregulated financial intermediaries that facilitate the creation of credit across the global financial system outside of the normal [banking](bank.md) system.
 
-See also [regulatory-arbitrage](regulatory-arbitrage.md).
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+See also [regulatory-arbitrage](regulatory-arbitrage.md).
+
+## References
+1. Allen, Hilary J. 2022. ‘DeFi: Shadow Banking 2.0?’ William & Mary Law Review, Forthcoming.
+* Steele, Graham. 2021. ‘The Miner of Last Resort: Digital Currency, Shadow Money and the Role of the Central Bank’. Technology and Government, Emerald Studies in Media and Communications, Forthcoming.
+* Gorton, Gary B., and Jeffery Zhang. 2021. ‘Taming Wildcat Stablecoins’. SSRN Electronic Journal. https://doi.org/10.2139/ssrn.3888752.
+* Malloy, Matthew, and David Lowe. 2021. ‘Global Stablecoins: Monetary Policy Implementation Considerations from the U.S. Perspective’. Finance and Economics Discussion Series 2021 (020): 1–14. https://doi.org/10.17016/feds.2021.020.
+* Pupolizio, Ivan. 2021. ‘From Libra to Diem. The Pursuit of a Global Private Currency’. Global Jurist. https://doi.org/10.1515/gj-2021-0055.
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