ICO Initial Coin Offering
ICO is an online crowdfunding event that allows investors to buy tokens directly from a seller or project at a pre-planned sale in exchange for either cryptocurrency or fiat currency.
IEO Initial Exchange Offering
IEO is a fundraising token sale administered by a cryptocurrency exchange on behalf of a seller or project. The coin or token will then be listed on the exchange.
STO Security Token Offering
An STO is a fundraising sale where the token sold represents an investment contract into an underlying asset or an ownership or tokenized share.
White Papers are easy to find since authors use them to describe and promote the projects they propose. Here are a few well known examples ranging from the elegantly simple to highly complex...
Bitcoin: A Peer-to-Peer Electronic Cash System (2008)
NEO White Paper : A distributed network for the Smart Economy (2014)
Monero White Paper: CryptoNote 2.0 (2014) Annotated White Paper Monero Research Lab Papers
Cardano Philosophy White Paper (2015) Academic Papers
and some guidelines for writing them:
White Papers (Purdue Owl) What is a White Paper? Purpose, Organization and Style.
"Writers typically use this genre when they argue a specific position or propose a solution to a problem, addressing the audience outside of their organization."
How to Write White Papers (Wiki How)